From e663d100a794d6ca92730831dc419bc1d18493bc Mon Sep 17 00:00:00 2001
From: Rishabh Chawla <rishabh31121999@gmail.com>
Date: Wed, 18 Mar 2020 15:47:02 +0530
Subject: [PATCH 01/43] chore: use commander

---
 packages/webpack-cli/lib/bootstrap.js        | 27 ++++---------
 packages/webpack-cli/lib/utils/arg-parser.js | 41 ++++++++++++++++++++
 packages/webpack-cli/lib/webpack-cli.js      | 15 +++++--
 packages/webpack-cli/package.json            |  1 +
 4 files changed, 62 insertions(+), 22 deletions(-)
 create mode 100644 packages/webpack-cli/lib/utils/arg-parser.js

diff --git a/packages/webpack-cli/lib/bootstrap.js b/packages/webpack-cli/lib/bootstrap.js
index 485c129a259..d5f15344855 100644
--- a/packages/webpack-cli/lib/bootstrap.js
+++ b/packages/webpack-cli/lib/bootstrap.js
@@ -2,7 +2,7 @@ const WebpackCLI = require('./webpack-cli');
 const { core, commands } = require('./utils/cli-flags');
 const logger = require('./utils/logger');
 const cliExecuter = require('./utils/cli-executer');
-
+const argParser = require('./utils/arg-parser');
 require('./utils/process-log');
 
 process.title = 'webpack-cli';
@@ -21,7 +21,7 @@ const isCommandUsed = (commands) =>
     });
 
 const resolveNegatedArgs = (args) => {
-    args._unknown.forEach((arg, idx) => {
+    args.forEach((arg, idx) => {
         if (arg.includes('--') || arg.includes('--no')) {
             const argPair = arg.split('=');
             const optName = arg.includes('--no') ? argPair[0].slice(5) : argPair[0].slice(2);
@@ -36,24 +36,14 @@ const resolveNegatedArgs = (args) => {
             if (cliFlag) {
                 args[cliFlag.group][optName] = argValue;
                 args._all[optName] = argValue;
-                args._unknown[idx] = null;
+                args.args[idx] = null;
             }
         }
     });
 };
 
 async function runCLI(cli, commandIsUsed) {
-    let args;
-    const helpFlagExists = isFlagPresent(process.argv, 'help');
-    const versionFlagExists = isFlagPresent(process.argv, 'version') || isFlagPresent(process.argv, '-v');
-
-    if (helpFlagExists) {
-        cli.runHelp(process.argv);
-        return;
-    } else if (versionFlagExists) {
-        cli.runVersion(commandIsUsed);
-        return;
-    }
+    const parsedArgs = argParser('webpack', core, process.argv, cli.runHelp, cli.runVersion);
 
     if (commandIsUsed) {
         commandIsUsed.defaultOption = true;
@@ -61,10 +51,9 @@ async function runCLI(cli, commandIsUsed) {
         return await cli.runCommand(commandIsUsed, ...args);
     } else {
         try {
-            args = cli.commandLineArgs(core, { stopAtFirstUnknown: false, partial: true });
-            if (args._unknown) {
-                resolveNegatedArgs(args);
-                args._unknown
+            if (parsedArgs.args.length > 0) {
+                resolveNegatedArgs(parsedArgs.args);
+                parsedArgs.args
                     .filter((e) => e)
                     .forEach((unknown) => {
                         logger.warn('Unknown argument:', unknown);
@@ -72,7 +61,7 @@ async function runCLI(cli, commandIsUsed) {
                 cliExecuter();
                 return;
             }
-            const result = await cli.run(args, core);
+            const result = await cli.run(parsedArgs.opts(), core);
             if (!result) {
                 return;
             }
diff --git a/packages/webpack-cli/lib/utils/arg-parser.js b/packages/webpack-cli/lib/utils/arg-parser.js
new file mode 100644
index 00000000000..0ccd86f9a26
--- /dev/null
+++ b/packages/webpack-cli/lib/utils/arg-parser.js
@@ -0,0 +1,41 @@
+const commander = require("commander");
+
+/**
+ *  Creates Argument parser corresponding to the supplied options
+ *  parse the args and return the result
+ *
+ * @param {object[]} options Array of objects with details about flags
+ * @param {string[]} args process.argv or it's subset
+ */
+function argParser(name, options, args, helpFunction, versionFunction) {
+    const parser = new commander.Command();
+    // Set parser name
+    parser.name(name);
+
+    // Use customized version output
+    parser.on('option:version', () => {
+        versionFunction(args);
+        process.exit(0);
+    });
+
+    // Use customised help output
+    parser.on('option:help', () => {
+        helpFunction(args);
+        process.exit(0);
+    });
+
+    // Allow execution if unknown arguments are present
+    parser.allowUnknownOption(true);
+
+    // Register options on the parser
+    options.reduce((parserInstance, option) => {
+        const flags = option.alias ? `-${option.alias}, --${option.name}` : `--${option.name}`;
+        const flagsWithType = option.type !== Boolean ? flags + ' [type]' : flags;
+        parserInstance.option(flagsWithType, option.description, option.defaultValue);
+        return parserInstance;
+    }, parser);
+
+    return parser.parse(args);
+}
+
+module.exports = argParser;
diff --git a/packages/webpack-cli/lib/webpack-cli.js b/packages/webpack-cli/lib/webpack-cli.js
index 12e1b925229..d2af6738dab 100644
--- a/packages/webpack-cli/lib/webpack-cli.js
+++ b/packages/webpack-cli/lib/webpack-cli.js
@@ -36,12 +36,12 @@ class WebpackCLI extends GroupHelper {
         this.outputConfiguration = {};
     }
     setMappedGroups(args, inlineOptions) {
-        const { _all } = args;
-        Object.keys(_all).forEach((key) => {
-            this.setGroupMap(key, _all[key], inlineOptions);
+        Object.keys(args).forEach((key) => {
+            this.setGroupMap(this._toKebabCase(key), args[key], inlineOptions);
         });
     }
     setGroupMap(key, val, inlineOptions) {
+        if (val === undefined) return;
         const opt = inlineOptions.find((opt) => opt.name === key);
         const groupName = opt.group;
         if (this.groupMap.has(groupName)) {
@@ -89,6 +89,15 @@ class WebpackCLI extends GroupHelper {
     getCoreFlags() {
         return core;
     }
+
+    /**
+     * Convert camelcase to kebabcase
+     * @param {string} string
+     */
+    _toKebabCase(string) {
+        return string.replace(/([a-z0-9])([A-Z])/g, '$1-$2').toLowerCase();
+    }
+
     /**
      * Based on the parsed keys, the function will import and create
      * a group that handles respective values
diff --git a/packages/webpack-cli/package.json b/packages/webpack-cli/package.json
index bf205953041..f95da5296c3 100644
--- a/packages/webpack-cli/package.json
+++ b/packages/webpack-cli/package.json
@@ -29,6 +29,7 @@
     "chalk": "^3.0.0",
     "command-line-args": "^5.1.1",
     "command-line-usage": "^6.1.0",
+    "commander": "^5.0.0",
     "enquirer": "^2.3.4",
     "execa": "^4.0.0",
     "import-local": "^3.0.2",

From 87403bfb9a07eed6d5a38c63099c8cf50068bbab Mon Sep 17 00:00:00 2001
From: Rishabh Chawla <rishabh31121999@gmail.com>
Date: Wed, 18 Mar 2020 16:25:11 +0530
Subject: [PATCH 02/43] chore: add support for help and version command

---
 packages/webpack-cli/lib/bootstrap.js | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/packages/webpack-cli/lib/bootstrap.js b/packages/webpack-cli/lib/bootstrap.js
index d5f15344855..0f3901f1aa9 100644
--- a/packages/webpack-cli/lib/bootstrap.js
+++ b/packages/webpack-cli/lib/bootstrap.js
@@ -45,6 +45,16 @@ const resolveNegatedArgs = (args) => {
 async function runCLI(cli, commandIsUsed) {
     const parsedArgs = argParser('webpack', core, process.argv, cli.runHelp, cli.runVersion);
 
+    if (parsedArgs.args.includes('help')) {
+        cli.runHelp(process.argv);
+        process.exit(0);
+    }
+
+    if (parsedArgs.args.includes('version')) {
+        cli.runVersion();
+        process.exit(0);
+    }
+
     if (commandIsUsed) {
         commandIsUsed.defaultOption = true;
         args = normalizeFlags(process.argv, commandIsUsed);

From ec8c4749240ab3ab0f8298de48c4d60c28fb21c1 Mon Sep 17 00:00:00 2001
From: Rishabh Chawla <rishabh31121999@gmail.com>
Date: Wed, 18 Mar 2020 16:49:06 +0530
Subject: [PATCH 03/43] chore: remove duplicate code for no-mode

---
 packages/webpack-cli/lib/groups/ZeroConfigGroup.js | 5 +----
 test/no-mode/no-mode.test.js                       | 4 ++--
 2 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/packages/webpack-cli/lib/groups/ZeroConfigGroup.js b/packages/webpack-cli/lib/groups/ZeroConfigGroup.js
index 26c5daeed26..2baedb23ea2 100644
--- a/packages/webpack-cli/lib/groups/ZeroConfigGroup.js
+++ b/packages/webpack-cli/lib/groups/ZeroConfigGroup.js
@@ -20,7 +20,7 @@ class ZeroConfigGroup extends GroupHelper {
         if (process.env.NODE_ENV && (process.env.NODE_ENV === PRODUCTION || process.env.NODE_ENV === DEVELOPMENT)) {
             return process.env.NODE_ENV;
         } else {
-            if ((this.args.mode || this.args.noMode) && (this.args.dev || this.args.prod)) {
+            if ((this.args.mode !== undefined ) && (this.args.dev || this.args.prod)) {
                 logger.warn(
                     `You provided both ${this.args.mode ? 'mode' : 'no-mode'} and ${
                         this.args.prod ? '--prod' : '--dev'
@@ -32,9 +32,6 @@ class ZeroConfigGroup extends GroupHelper {
                     return NONE;
                 }
             }
-            if (this.args.noMode && this.args.mode) {
-                logger.warn('You Provided both mode and no-mode arguments. You Should Provide just one. "mode" will be used.');
-            }
             if (this.args.mode) {
                 return this.args.mode;
             }
diff --git a/test/no-mode/no-mode.test.js b/test/no-mode/no-mode.test.js
index 5eff202d82e..aa71c614dfe 100644
--- a/test/no-mode/no-mode.test.js
+++ b/test/no-mode/no-mode.test.js
@@ -40,7 +40,7 @@ describe('no-mode flag', () => {
 
     it('should load a production config when --mode=production & --no-mode are passed', (done) => {
         const { stderr, stdout } = run(__dirname, ['--mode', 'production', '--no-mode']);
-        expect(stderr).toContain('"mode" will be used');
+        expect(stderr).toBeFalsy();
         expect(stdout).toBeTruthy();
 
         stat(resolve(__dirname, './bin/main.js'), (err, stats) => {
@@ -52,7 +52,7 @@ describe('no-mode flag', () => {
 
     it('should load a development config when --mode=development and --no-mode are passed', (done) => {
         const { stderr, stdout } = run(__dirname, ['--mode', 'development', '--no-mode']);
-        expect(stderr).toContain('"mode" will be used');
+        expect(stderr).toBeFalsy();
         expect(stdout).toBeTruthy();
 
         stat(resolve(__dirname, './bin/main.js'), (err, stats) => {

From f7009ae9bfb805e86328744b7f6a591224b28835 Mon Sep 17 00:00:00 2001
From: Rishabh Chawla <rishabh31121999@gmail.com>
Date: Wed, 18 Mar 2020 16:55:25 +0530
Subject: [PATCH 04/43] chore: create helpers

---
 packages/webpack-cli/lib/utils/helpers.js | 10 ++++++++++
 packages/webpack-cli/lib/webpack-cli.js   | 11 ++---------
 2 files changed, 12 insertions(+), 9 deletions(-)
 create mode 100644 packages/webpack-cli/lib/utils/helpers.js

diff --git a/packages/webpack-cli/lib/utils/helpers.js b/packages/webpack-cli/lib/utils/helpers.js
new file mode 100644
index 00000000000..34fdd0a55d4
--- /dev/null
+++ b/packages/webpack-cli/lib/utils/helpers.js
@@ -0,0 +1,10 @@
+/**
+ * Convert camelCase to kebab-case
+ * @param {string} str input string in camelCase
+ * @returns {string} output string in kebab-case
+ */
+function toKebabCase(str) {
+    return str.replace(/([a-z0-9])([A-Z])/g, '$1-$2').toLowerCase()
+}
+
+module.exports = { toKebabCase };
diff --git a/packages/webpack-cli/lib/webpack-cli.js b/packages/webpack-cli/lib/webpack-cli.js
index d2af6738dab..a5539442529 100644
--- a/packages/webpack-cli/lib/webpack-cli.js
+++ b/packages/webpack-cli/lib/webpack-cli.js
@@ -5,7 +5,7 @@ const { Compiler } = require('./utils/Compiler');
 const { groups, core } = require('./utils/cli-flags');
 const webpackMerge = require('webpack-merge');
 const commandArgs = require('command-line-args');
-
+const { toKebabCase } = require('./utils/helpers');
 const defaultCommands = {
     init: 'init',
     loader: 'generate-loader',
@@ -37,7 +37,7 @@ class WebpackCLI extends GroupHelper {
     }
     setMappedGroups(args, inlineOptions) {
         Object.keys(args).forEach((key) => {
-            this.setGroupMap(this._toKebabCase(key), args[key], inlineOptions);
+            this.setGroupMap(toKebabCase(key), args[key], inlineOptions);
         });
     }
     setGroupMap(key, val, inlineOptions) {
@@ -90,13 +90,6 @@ class WebpackCLI extends GroupHelper {
         return core;
     }
 
-    /**
-     * Convert camelcase to kebabcase
-     * @param {string} string
-     */
-    _toKebabCase(string) {
-        return string.replace(/([a-z0-9])([A-Z])/g, '$1-$2').toLowerCase();
-    }
 
     /**
      * Based on the parsed keys, the function will import and create

From af62829d89c39e8253fdc6874c6c4ca17e5b12c1 Mon Sep 17 00:00:00 2001
From: Rishabh Chawla <rishabh31121999@gmail.com>
Date: Thu, 19 Mar 2020 14:55:37 +0530
Subject: [PATCH 05/43] chore: remove global flag

---
 .../webpack-cli/lib/groups/AdvancedGroup.js   | 53 -------------------
 packages/webpack-cli/lib/utils/cli-flags.js   |  9 ----
 test/global/global.test.js                    | 53 -------------------
 test/global/global1.js                        |  1 -
 test/global/global2.js                        |  1 -
 test/global/index.js                          |  5 --
 6 files changed, 122 deletions(-)
 delete mode 100644 test/global/global.test.js
 delete mode 100644 test/global/global1.js
 delete mode 100644 test/global/global2.js
 delete mode 100644 test/global/index.js

diff --git a/packages/webpack-cli/lib/groups/AdvancedGroup.js b/packages/webpack-cli/lib/groups/AdvancedGroup.js
index c3abafb23e4..98dea3e4e4b 100644
--- a/packages/webpack-cli/lib/groups/AdvancedGroup.js
+++ b/packages/webpack-cli/lib/groups/AdvancedGroup.js
@@ -77,59 +77,6 @@ class AdvancedGroup extends GroupHelper {
         if (args.target) {
             options.target = args.target;
         }
-
-        if (args.global) {
-            const globalArrLen = args.global.length;
-            if (!globalArrLen) {
-                logger.warn('Argument to global flag is none');
-                return;
-            }
-            if (globalArrLen === 1) {
-                logger.warn('Argument to global flag expected a key/value pair');
-                return;
-            }
-
-            const providePluginObject = {};
-            args.global.forEach((arg, idx) => {
-                const isKey = idx % 2 === 0;
-                const isConcatArg = arg.includes('=');
-                if (isKey && isConcatArg) {
-                    const splitIdx = arg.indexOf('=');
-                    const argVal = arg.substr(splitIdx + 1);
-                    const argKey = arg.substr(0, splitIdx);
-                    if (!argVal.length) {
-                        logger.warn(`Found unmatching value for global flag key '${argKey}'`);
-                        return;
-                    }
-                    // eslint-disable-next-line no-prototype-builtins
-                    if (providePluginObject.hasOwnProperty(argKey)) {
-                        logger.warn(`Overriding key '${argKey}' for global flag`);
-                    }
-                    providePluginObject[argKey] = argVal;
-                    return;
-                }
-                if (isKey) {
-                    const nextArg = args.global[idx + 1];
-                    // eslint-disable-next-line no-prototype-builtins
-                    if (providePluginObject.hasOwnProperty(arg)) {
-                        logger.warn(`Overriding key '${arg}' for global flag`);
-                    }
-                    if (!nextArg) {
-                        logger.warn(`Found unmatching value for global flag key '${arg}'`);
-                        return;
-                    }
-                    providePluginObject[arg] = nextArg;
-                }
-            });
-
-            const { ProvidePlugin } = require('webpack');
-            const globalVal = new ProvidePlugin(providePluginObject);
-            if (options && options.plugins) {
-                options.plugins.unshift(globalVal);
-            } else {
-                options.plugins = [globalVal];
-            }
-        }
     }
     run() {
         this.resolveOptions();
diff --git a/packages/webpack-cli/lib/utils/cli-flags.js b/packages/webpack-cli/lib/utils/cli-flags.js
index 28b7a832f2e..a4e7f9ae595 100644
--- a/packages/webpack-cli/lib/utils/cli-flags.js
+++ b/packages/webpack-cli/lib/utils/cli-flags.js
@@ -147,15 +147,6 @@ module.exports = {
             description: 'Load a given plugin',
             link: 'https://webpack.js.org/plugins/',
         },
-        {
-            name: 'global',
-            usage: '--global myVar ./global.js',
-            alias: 'g',
-            type: String,
-            multiple: true,
-            group: ADVANCED_GROUP,
-            description: 'Declares and exposes a global variable',
-        },
         {
             name: 'target',
             usage: '--target',
diff --git a/test/global/global.test.js b/test/global/global.test.js
deleted file mode 100644
index 3e284d1df01..00000000000
--- a/test/global/global.test.js
+++ /dev/null
@@ -1,53 +0,0 @@
-'use strict';
-
-const path = require('path');
-const execa = require('execa');
-const { sync: spawnSync } = execa;
-
-const { run } = require('../utils/test-utils');
-
-describe('global flag', () => {
-    it('warns if there are no arguments to flag', () => {
-        const { stderr } = run(__dirname, ['--global']);
-        expect(stderr).toContain('Argument to global flag is none');
-    });
-
-    it('warns if there are no value for key', () => {
-        const { stderr } = run(__dirname, ['--global', 'myVar']);
-        expect(stderr).toContain('Argument to global flag expected a key/value pair');
-    });
-
-    it('is able to inject one variable to global scope', () => {
-        const { stdout } = run(__dirname, ['--global', 'myVar', './global1.js']);
-        expect(stdout).toContain('option has not been set, webpack will fallback to');
-        const executable = path.join(__dirname, './bin/main.js');
-        const bundledScript = spawnSync('node', [executable]);
-        expect(bundledScript.stdout).toEqual('myVar ./global1.js');
-    });
-
-    it('is able to inject multiple variables to global scope', () => {
-        const { stdout } = run(__dirname, ['--global', 'myVar', './global1.js', '--global', 'myVar2', './global2.js']);
-        expect(stdout).toContain('option has not been set, webpack will fallback to');
-        const executable = path.join(__dirname, './bin/main.js');
-        const bundledScript = spawnSync('node', [executable]);
-        expect(bundledScript.stdout).toEqual('myVar ./global1.js\nmyVar ./global2.js');
-    });
-
-    it('understands = syntax', () => {
-        const { stdout } = run(__dirname, ['--global', 'myVar', './global1.js', '--global', 'myVar2=./global2.js']);
-        expect(stdout).toContain('option has not been set, webpack will fallback to');
-        const executable = path.join(__dirname, './bin/main.js');
-        const bundledScript = spawnSync('node', [executable]);
-        expect(bundledScript.stdout).toEqual('myVar ./global1.js\nmyVar ./global2.js');
-    });
-
-    it('warns on multiple flags that are inconsistent', () => {
-        const result = run(__dirname, ['--global', 'myVar', './global1.js', '--global', 'myVar2']);
-        // eslint-disable-next-line
-        expect(result.stderr).toContain("Found unmatching value for global flag key 'myVar2'");
-
-        const result2 = run(__dirname, ['--global', 'myVar', './global1.js', '--global', 'myVar2=']);
-        // eslint-disable-next-line
-        expect(result2.stderr).toContain("Found unmatching value for global flag key 'myVar2'");
-    });
-});
diff --git a/test/global/global1.js b/test/global/global1.js
deleted file mode 100644
index e7d024ed70b..00000000000
--- a/test/global/global1.js
+++ /dev/null
@@ -1 +0,0 @@
-module.exports = 'myVar ./global1.js';
diff --git a/test/global/global2.js b/test/global/global2.js
deleted file mode 100644
index c80fbb2b620..00000000000
--- a/test/global/global2.js
+++ /dev/null
@@ -1 +0,0 @@
-module.exports = 'myVar ./global2.js';
diff --git a/test/global/index.js b/test/global/index.js
deleted file mode 100644
index c832cbbeaeb..00000000000
--- a/test/global/index.js
+++ /dev/null
@@ -1,5 +0,0 @@
-console.log(myVar);
-
-try {
-    console.log(myVar2);
-} catch(e) {}

From eab3500685a7114630921abefe1f758fb4b39147 Mon Sep 17 00:00:00 2001
From: Rishabh Chawla <rishabh31121999@gmail.com>
Date: Thu, 19 Mar 2020 15:43:26 +0530
Subject: [PATCH 06/43] chore: improve arg parsing and tests

---
 packages/webpack-cli/lib/groups/StatsGroup.js      |  3 +++
 packages/webpack-cli/lib/groups/ZeroConfigGroup.js |  5 +++++
 packages/webpack-cli/lib/utils/cli-flags.js        | 11 ++---------
 test/config/basic/basic-config.test.js             |  2 +-
 test/entry/defaults-index/entry-multi-args.test.js |  2 +-
 test/stats/stats.test.js                           |  2 +-
 6 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/packages/webpack-cli/lib/groups/StatsGroup.js b/packages/webpack-cli/lib/groups/StatsGroup.js
index 36fc0e30ccd..b8654e8c5c5 100644
--- a/packages/webpack-cli/lib/groups/StatsGroup.js
+++ b/packages/webpack-cli/lib/groups/StatsGroup.js
@@ -23,6 +23,9 @@ class StatsGroup extends GroupHelper {
                 this.opts.option.stats = {
                     verbose: true,
                 };
+            } else if (!StatsGroup.validOptions().includes(this.args.stats)) {
+                logger.warn(`'${this.args.stats}' is invalid value for stats. Using 'normal' option for stats`);
+                this.opts.options.stats = 'normal';
             } else {
                 this.opts.options.stats = this.args.stats;
             }
diff --git a/packages/webpack-cli/lib/groups/ZeroConfigGroup.js b/packages/webpack-cli/lib/groups/ZeroConfigGroup.js
index 2baedb23ea2..0d62ccb62bb 100644
--- a/packages/webpack-cli/lib/groups/ZeroConfigGroup.js
+++ b/packages/webpack-cli/lib/groups/ZeroConfigGroup.js
@@ -32,7 +32,12 @@ class ZeroConfigGroup extends GroupHelper {
                     return NONE;
                 }
             }
+
             if (this.args.mode) {
+                if (this.args.mode !== PRODUCTION && this.args.mode !== DEVELOPMENT && this.args.mode !== NONE) {
+                    logger.warn('You provided an invalid value for "mode" option.');
+                    return PRODUCTION;
+                }
                 return this.args.mode;
             }
             if (this.args.prod) {
diff --git a/packages/webpack-cli/lib/utils/cli-flags.js b/packages/webpack-cli/lib/utils/cli-flags.js
index a4e7f9ae595..e6cc3012aaa 100644
--- a/packages/webpack-cli/lib/utils/cli-flags.js
+++ b/packages/webpack-cli/lib/utils/cli-flags.js
@@ -222,15 +222,8 @@ module.exports = {
         },
         {
             name: 'mode',
-            usage: '--mode <development | production | none>',
-            type: (value) => {
-                if (value === 'development' || value === 'production' || value === 'none') {
-                    return value;
-                } else {
-                    logger.warn('You provided an invalid value for "mode" option.');
-                    return 'production';
-                }
-            },
+            usage: '--mode <development | production>',
+            type: String,
             group: ZERO_CONFIG_GROUP,
             description: 'Defines the mode to pass to webpack',
             link: 'https://webpack.js.org/concepts/#mode',
diff --git a/test/config/basic/basic-config.test.js b/test/config/basic/basic-config.test.js
index a98e3492652..dec2eef82bb 100644
--- a/test/config/basic/basic-config.test.js
+++ b/test/config/basic/basic-config.test.js
@@ -6,7 +6,7 @@ const { run } = require('../../utils/test-utils');
 describe('basic config file', () => {
     it('is able to understand and parse a very basic configuration file', (done) => {
         const { stdout, stderr } = run(__dirname, ['-c', resolve(__dirname, 'webpack.config.js'), '--output', './binary/a.bundle.js']);
-        expect(stderr).toContain('Duplicate flags found, defaulting to last set value');
+        expect(stderr).toBeFalsy();
         expect(stdout).not.toBe(undefined);
         stat(resolve(__dirname, './binary/a.bundle.js'), (err, stats) => {
             expect(err).toBe(null);
diff --git a/test/entry/defaults-index/entry-multi-args.test.js b/test/entry/defaults-index/entry-multi-args.test.js
index abc7a291a98..270e0f8a94d 100644
--- a/test/entry/defaults-index/entry-multi-args.test.js
+++ b/test/entry/defaults-index/entry-multi-args.test.js
@@ -19,7 +19,7 @@ describe('single entry flag index present', () => {
 
     it('finds default index file, compiles and overrides with flags successfully', (done) => {
         const { stderr } = run(__dirname, ['--output', 'bin/main.js']);
-        expect(stderr).toContain('Duplicate flags found, defaulting to last set value');
+        expect(stderr).toBeFalsy();
 
         stat(resolve(__dirname, './bin/main.js'), (err, stats) => {
             expect(err).toBe(null);
diff --git a/test/stats/stats.test.js b/test/stats/stats.test.js
index 7eca9cf0e2e..656a6633825 100644
--- a/test/stats/stats.test.js
+++ b/test/stats/stats.test.js
@@ -48,7 +48,7 @@ describe('stats flag', () => {
     it('should warn when an unknown flag stats value is passed', () => {
         const { stderr, stdout } = run(__dirname, ['--stats', 'foo']);
         expect(stderr).toBeTruthy();
-        expect(stderr).toContain('No value recognised for "stats" option');
+        expect(stderr).toContain('invalid value for stats');
         expect(stdout).toBeTruthy();
     });
 });

From ab17bf068e8763e9e090bfbd63f1edf107bc705f Mon Sep 17 00:00:00 2001
From: Rishabh Chawla <rishabh31121999@gmail.com>
Date: Sat, 21 Mar 2020 12:39:25 +0530
Subject: [PATCH 07/43] chore: remove command-line-args

---
 packages/webpack-cli/lib/webpack-cli.js | 5 -----
 packages/webpack-cli/package.json       | 1 -
 2 files changed, 6 deletions(-)

diff --git a/packages/webpack-cli/lib/webpack-cli.js b/packages/webpack-cli/lib/webpack-cli.js
index a5539442529..de12593f4f9 100644
--- a/packages/webpack-cli/lib/webpack-cli.js
+++ b/packages/webpack-cli/lib/webpack-cli.js
@@ -81,11 +81,6 @@ class WebpackCLI extends GroupHelper {
         return options;
     }
 
-    // It exposes "command-line-args" function
-    commandLineArgs(...args) {
-        return commandArgs(...args);
-    }
-
     getCoreFlags() {
         return core;
     }
diff --git a/packages/webpack-cli/package.json b/packages/webpack-cli/package.json
index f95da5296c3..397fd074556 100644
--- a/packages/webpack-cli/package.json
+++ b/packages/webpack-cli/package.json
@@ -27,7 +27,6 @@
     "@webpack-cli/info": "^1.0.1-alpha.4",
     "ansi-escapes": "^4.3.1",
     "chalk": "^3.0.0",
-    "command-line-args": "^5.1.1",
     "command-line-usage": "^6.1.0",
     "commander": "^5.0.0",
     "enquirer": "^2.3.4",

From 327fc7d99ad2b41d81dff0f686a02d045c6e4a24 Mon Sep 17 00:00:00 2001
From: Rishabh Chawla <rishabh31121999@gmail.com>
Date: Sat, 21 Mar 2020 12:59:22 +0530
Subject: [PATCH 08/43] chore: remove instance of command-line-args

---
 packages/webpack-cli/lib/bootstrap.js        |  5 ++--
 packages/webpack-cli/lib/utils/arg-parser.js | 26 +++++++++++---------
 packages/webpack-cli/lib/webpack-cli.js      |  1 -
 3 files changed, 17 insertions(+), 15 deletions(-)

diff --git a/packages/webpack-cli/lib/bootstrap.js b/packages/webpack-cli/lib/bootstrap.js
index 0f3901f1aa9..43feb670daf 100644
--- a/packages/webpack-cli/lib/bootstrap.js
+++ b/packages/webpack-cli/lib/bootstrap.js
@@ -98,9 +98,8 @@ async function runCLI(cli, commandIsUsed) {
                 const newArgKeys = Object.keys(argsMap).filter((arg) => !keysToDelete.includes(argsMap[arg].pos));
                 // eslint-disable-next-line require-atomic-updates
                 process.argv = newArgKeys;
-                args = cli.commandLineArgs(core, { stopAtFirstUnknown: false, partial: true });
-
-                await cli.run(args, core);
+                args = argParser("", core, process.argv).opts;
+                await cli.run(args.opts(), core);
                 process.stdout.write('\n');
                 logger.warn('Duplicate flags found, defaulting to last set value');
             } else {
diff --git a/packages/webpack-cli/lib/utils/arg-parser.js b/packages/webpack-cli/lib/utils/arg-parser.js
index 0ccd86f9a26..3053c0a7622 100644
--- a/packages/webpack-cli/lib/utils/arg-parser.js
+++ b/packages/webpack-cli/lib/utils/arg-parser.js
@@ -7,22 +7,26 @@ const commander = require("commander");
  * @param {object[]} options Array of objects with details about flags
  * @param {string[]} args process.argv or it's subset
  */
-function argParser(name, options, args, helpFunction, versionFunction) {
+function argParser(name = "", options, args, helpFunction, versionFunction) {
     const parser = new commander.Command();
     // Set parser name
     parser.name(name);
 
-    // Use customized version output
-    parser.on('option:version', () => {
-        versionFunction(args);
-        process.exit(0);
-    });
+    // Use customized version output if available
+    if (versionFunction) {
+        parser.on('option:version', () => {
+            versionFunction(args);
+            process.exit(0);
+        });
+    }
 
-    // Use customised help output
-    parser.on('option:help', () => {
-        helpFunction(args);
-        process.exit(0);
-    });
+    // Use customised help output is avaliable
+    if (helpFunction) {
+        parser.on('option:help', () => {
+            helpFunction(args);
+            process.exit(0);
+        });
+    }
 
     // Allow execution if unknown arguments are present
     parser.allowUnknownOption(true);
diff --git a/packages/webpack-cli/lib/webpack-cli.js b/packages/webpack-cli/lib/webpack-cli.js
index de12593f4f9..03fe305be4a 100644
--- a/packages/webpack-cli/lib/webpack-cli.js
+++ b/packages/webpack-cli/lib/webpack-cli.js
@@ -4,7 +4,6 @@ const GroupHelper = require('./utils/GroupHelper');
 const { Compiler } = require('./utils/Compiler');
 const { groups, core } = require('./utils/cli-flags');
 const webpackMerge = require('webpack-merge');
-const commandArgs = require('command-line-args');
 const { toKebabCase } = require('./utils/helpers');
 const defaultCommands = {
     init: 'init',

From 05173d8741d3c4efc836b2363c1bb6ccd1f248b6 Mon Sep 17 00:00:00 2001
From: Rishabh Chawla <rishabh31121999@gmail.com>
Date: Sat, 21 Mar 2020 13:19:31 +0530
Subject: [PATCH 09/43] chore: add explaination to the change

---
 packages/webpack-cli/lib/groups/OutputGroup.js | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/packages/webpack-cli/lib/groups/OutputGroup.js b/packages/webpack-cli/lib/groups/OutputGroup.js
index be24b101b1d..97e3ba0d2af 100644
--- a/packages/webpack-cli/lib/groups/OutputGroup.js
+++ b/packages/webpack-cli/lib/groups/OutputGroup.js
@@ -27,7 +27,10 @@ class OutputGroup extends GroupHelper {
         const { args } = this;
         if (args) {
             const { output } = args;
-            if (!output) {
+            // TODO: Remove comment before merge
+            // We need to show warning when empty output flag is supplied
+            // which is set to boolean true by commander
+            if (!output || output === true) {
                 return;
             }
             const outputInfo = path.parse(output);

From 5244654993172d084555912575e36438907f6667 Mon Sep 17 00:00:00 2001
From: Rishabh Chawla <rishabh31121999@gmail.com>
Date: Sun, 22 Mar 2020 17:51:37 +0530
Subject: [PATCH 10/43] chore: fix

---
 packages/webpack-cli/lib/bootstrap.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/webpack-cli/lib/bootstrap.js b/packages/webpack-cli/lib/bootstrap.js
index 43feb670daf..c3acc2e1dd7 100644
--- a/packages/webpack-cli/lib/bootstrap.js
+++ b/packages/webpack-cli/lib/bootstrap.js
@@ -98,7 +98,7 @@ async function runCLI(cli, commandIsUsed) {
                 const newArgKeys = Object.keys(argsMap).filter((arg) => !keysToDelete.includes(argsMap[arg].pos));
                 // eslint-disable-next-line require-atomic-updates
                 process.argv = newArgKeys;
-                args = argParser("", core, process.argv).opts;
+                args = argParser("", core, process.argv);
                 await cli.run(args.opts(), core);
                 process.stdout.write('\n');
                 logger.warn('Duplicate flags found, defaulting to last set value');

From 777f8e54318ded01f67c1ee2ad9be0f09e8bd036 Mon Sep 17 00:00:00 2001
From: Rishabh Chawla <rishabh31121999@gmail.com>
Date: Tue, 24 Mar 2020 18:20:34 +0530
Subject: [PATCH 11/43] chore: migrate serve package

---
 packages/serve/src/index.ts             | 31 +++++++++++++++----------
 packages/webpack-cli/lib/webpack-cli.js | 11 +++++++++
 2 files changed, 30 insertions(+), 12 deletions(-)

diff --git a/packages/serve/src/index.ts b/packages/serve/src/index.ts
index 3c4587efb75..c5788d8a39c 100644
--- a/packages/serve/src/index.ts
+++ b/packages/serve/src/index.ts
@@ -15,18 +15,25 @@ export default function serve(...args): void {
     const core = cli.getCoreFlags();
     // partial parsing usage: https://github.com/75lb/command-line-args/wiki/Partial-parsing
 
-    // since the webpack flags have the 'entry' option set as it's default option,
-    // we need to parse the dev server args first. Otherwise, the webpack parsing could snatch
-    // one of the dev server's options and set it to this 'entry' option.
-    // see: https://github.com/75lb/command-line-args/blob/master/doc/option-definition.md#optiondefaultoption--boolean
-    const devServerArgs = cli.commandLineArgs(devServer, { argv: args, partial: true });
-    const webpackArgs = cli.commandLineArgs(core, { argv: devServerArgs._unknown || [], stopAtFirstUnknown: false });
-    const finalArgs = argsToCamelCase(devServerArgs._all || {});
-    // pass along the 'hot' argument to the dev server if it exists
-    if (webpackArgs && webpackArgs._all && typeof webpackArgs._all.hot !== 'undefined') {
-        finalArgs['hot'] = webpackArgs._all.hot;
+	// since the webpack flags have the 'entry' option set as it's default option,
+	// we need to parse the dev server args first. Otherwise, the webpack parsing could snatch
+	// one of the dev server's options and set it to this 'entry' option.
+	// see: https://github.com/75lb/command-line-args/blob/master/doc/option-definition.md#optiondefaultoption--boolean
+	const devServerArgs = cli.argParser("", devServer, args);
+	const webpackArgs = cli.argParser("", core, devServerArgs.args);
+	const finalArgs = argsToCamelCase(devServerArgs.opts() || {});
+	// pass along the 'hot' argument to the dev server if it exists
+	if (webpackArgs && webpackArgs.opts() && typeof webpackArgs.opts().hot !== 'undefined') {
+		finalArgs['hot'] = webpackArgs.opts().hot;
     }
-    cli.getCompiler(webpackArgs, core).then((compiler): void => {
-        startDevServer(compiler, finalArgs);
+
+    Object.keys(finalArgs).forEach(arg => {
+        if (finalArgs[arg] === undefined) {
+            delete finalArgs[arg];
+        }
     });
+
+	cli.getCompiler(webpackArgs.opts(), core).then((compiler): void => {
+		startDevServer(compiler, finalArgs);
+	});
 }
diff --git a/packages/webpack-cli/lib/webpack-cli.js b/packages/webpack-cli/lib/webpack-cli.js
index 03fe305be4a..078b550bbf8 100644
--- a/packages/webpack-cli/lib/webpack-cli.js
+++ b/packages/webpack-cli/lib/webpack-cli.js
@@ -5,6 +5,8 @@ const { Compiler } = require('./utils/Compiler');
 const { groups, core } = require('./utils/cli-flags');
 const webpackMerge = require('webpack-merge');
 const { toKebabCase } = require('./utils/helpers');
+const argParser = require('./utils/arg-parser');
+
 const defaultCommands = {
     init: 'init',
     loader: 'generate-loader',
@@ -80,6 +82,15 @@ class WebpackCLI extends GroupHelper {
         return options;
     }
 
+    /**
+     * Expose commander argParser
+     * @param  {...any} args args for argParser
+     */
+    argParser(...args) {
+        return argParser(...args);
+    }
+
+
     getCoreFlags() {
         return core;
     }

From b9a49320144b5e45a64e67f15562a70051197ed5 Mon Sep 17 00:00:00 2001
From: Rishabh Chawla <rishabh31121999@gmail.com>
Date: Tue, 24 Mar 2020 18:48:22 +0530
Subject: [PATCH 12/43] chore: handle error

---
 packages/serve/src/index.ts | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/packages/serve/src/index.ts b/packages/serve/src/index.ts
index c5788d8a39c..f7cf6f26fc6 100644
--- a/packages/serve/src/index.ts
+++ b/packages/serve/src/index.ts
@@ -33,6 +33,10 @@ export default function serve(...args): void {
         }
     });
 
+    if (webpackArgs.args.length > 0) {
+        process.stderr.write(`Unknown argument: ${webpackArgs.args} flag`);
+    }
+
 	cli.getCompiler(webpackArgs.opts(), core).then((compiler): void => {
 		startDevServer(compiler, finalArgs);
 	});

From ad0cc8f2d1f7eefcb4944ff942532ef871f3f39e Mon Sep 17 00:00:00 2001
From: Rishabh Chawla <rishabh31121999@gmail.com>
Date: Thu, 26 Mar 2020 12:30:31 +0530
Subject: [PATCH 13/43] chore: reactor argparser

---
 packages/serve/src/index.ts                  | 27 +++++++++++---------
 packages/webpack-cli/lib/bootstrap.js        |  2 +-
 packages/webpack-cli/lib/utils/arg-parser.js |  2 +-
 3 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/packages/serve/src/index.ts b/packages/serve/src/index.ts
index f7cf6f26fc6..27a1a035f7e 100644
--- a/packages/serve/src/index.ts
+++ b/packages/serve/src/index.ts
@@ -1,7 +1,7 @@
-import { devServer } from 'webpack-dev-server/bin/cli-flags';
-import WebpackCLI from 'webpack-cli';
-import startDevServer from './startDevServer';
-import argsToCamelCase from './args-to-camel-case';
+import { devServer } from "webpack-dev-server/bin/cli-flags";
+import WebpackCLI from "webpack-cli";
+import startDevServer from "./startDevServer";
+import argsToCamelCase from "./args-to-camel-case";
 
 /**
  *
@@ -11,20 +11,22 @@ import argsToCamelCase from './args-to-camel-case';
  * @returns {Function} invokes the devServer API
  */
 export default function serve(...args): void {
-    const cli = new WebpackCLI();
-    const core = cli.getCoreFlags();
+	const cli = new WebpackCLI();
+	const core = cli.getCoreFlags();
+
     // partial parsing usage: https://github.com/75lb/command-line-args/wiki/Partial-parsing
 
 	// since the webpack flags have the 'entry' option set as it's default option,
 	// we need to parse the dev server args first. Otherwise, the webpack parsing could snatch
 	// one of the dev server's options and set it to this 'entry' option.
 	// see: https://github.com/75lb/command-line-args/blob/master/doc/option-definition.md#optiondefaultoption--boolean
-	const devServerArgs = cli.argParser("", devServer, args);
-	const webpackArgs = cli.argParser("", core, devServerArgs.args);
-	const finalArgs = argsToCamelCase(devServerArgs.opts() || {});
+	const devServerArgs = cli.argParser(devServer, args);
+	const webpackArgs = cli.argParser(core, args, process.title, cli.runHelp, cli.runVersion);
+
+    const finalArgs = argsToCamelCase(devServerArgs.opts() || {});
 	// pass along the 'hot' argument to the dev server if it exists
-	if (webpackArgs && webpackArgs.opts() && typeof webpackArgs.opts().hot !== 'undefined') {
-		finalArgs['hot'] = webpackArgs.opts().hot;
+	if (webpackArgs && webpackArgs.opts() && webpackArgs.opts().hot !== undefined) {
+        finalArgs['hot'] = webpackArgs.opts().hot;
     }
 
     Object.keys(finalArgs).forEach(arg => {
@@ -34,7 +36,8 @@ export default function serve(...args): void {
     });
 
     if (webpackArgs.args.length > 0) {
-        process.stderr.write(`Unknown argument: ${webpackArgs.args} flag`);
+        process.stderr.write(`Unknown argument: ${webpackArgs.args}`);
+        return;
     }
 
 	cli.getCompiler(webpackArgs.opts(), core).then((compiler): void => {
diff --git a/packages/webpack-cli/lib/bootstrap.js b/packages/webpack-cli/lib/bootstrap.js
index c3acc2e1dd7..8cc20b168d2 100644
--- a/packages/webpack-cli/lib/bootstrap.js
+++ b/packages/webpack-cli/lib/bootstrap.js
@@ -43,7 +43,7 @@ const resolveNegatedArgs = (args) => {
 };
 
 async function runCLI(cli, commandIsUsed) {
-    const parsedArgs = argParser('webpack', core, process.argv, cli.runHelp, cli.runVersion);
+    const parsedArgs = argParser(core, process.argv, process.title, cli.runHelp, cli.runVersion);
 
     if (parsedArgs.args.includes('help')) {
         cli.runHelp(process.argv);
diff --git a/packages/webpack-cli/lib/utils/arg-parser.js b/packages/webpack-cli/lib/utils/arg-parser.js
index 3053c0a7622..4fa97f4133a 100644
--- a/packages/webpack-cli/lib/utils/arg-parser.js
+++ b/packages/webpack-cli/lib/utils/arg-parser.js
@@ -7,7 +7,7 @@ const commander = require("commander");
  * @param {object[]} options Array of objects with details about flags
  * @param {string[]} args process.argv or it's subset
  */
-function argParser(name = "", options, args, helpFunction, versionFunction) {
+function argParser(options, args, name = "", helpFunction = undefined, versionFunction = undefined) {
     const parser = new commander.Command();
     // Set parser name
     parser.name(name);

From 1b3212d8ba9225fdf048c5f0af2787787093534f Mon Sep 17 00:00:00 2001
From: Rishabh Chawla <rishabh31121999@gmail.com>
Date: Thu, 26 Mar 2020 14:56:16 +0530
Subject: [PATCH 14/43] chore: get serve args from process.argv

---
 packages/serve/src/index.ts | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/packages/serve/src/index.ts b/packages/serve/src/index.ts
index 27a1a035f7e..fdab886157e 100644
--- a/packages/serve/src/index.ts
+++ b/packages/serve/src/index.ts
@@ -10,21 +10,17 @@ import argsToCamelCase from "./args-to-camel-case";
  * @param {String[]} args - args processed from the CLI
  * @returns {Function} invokes the devServer API
  */
-export default function serve(...args): void {
+export default function serve(): void {
 	const cli = new WebpackCLI();
 	const core = cli.getCoreFlags();
 
-    // partial parsing usage: https://github.com/75lb/command-line-args/wiki/Partial-parsing
+    const filteredArgs = process.argv.filter(arg => (arg != "serve"));
+    const devServerArgs = cli.argParser(devServer, filteredArgs);
+	const webpackArgs = cli.argParser(core, filteredArgs, process.title, cli.runHelp, cli.runVersion);
+    const finalArgs = argsToCamelCase(devServerArgs.opts() || {});
 
-	// since the webpack flags have the 'entry' option set as it's default option,
-	// we need to parse the dev server args first. Otherwise, the webpack parsing could snatch
-	// one of the dev server's options and set it to this 'entry' option.
-	// see: https://github.com/75lb/command-line-args/blob/master/doc/option-definition.md#optiondefaultoption--boolean
-	const devServerArgs = cli.argParser(devServer, args);
-	const webpackArgs = cli.argParser(core, args, process.title, cli.runHelp, cli.runVersion);
 
-    const finalArgs = argsToCamelCase(devServerArgs.opts() || {});
-	// pass along the 'hot' argument to the dev server if it exists
+    // pass along the 'hot' argument to the dev server if it exists
 	if (webpackArgs && webpackArgs.opts() && webpackArgs.opts().hot !== undefined) {
         finalArgs['hot'] = webpackArgs.opts().hot;
     }

From 503a1f77f82935662d60fb160dabb3be63e4bbcd Mon Sep 17 00:00:00 2001
From: Rishabh Chawla <rishabh31121999@gmail.com>
Date: Thu, 26 Mar 2020 14:59:50 +0530
Subject: [PATCH 15/43] chore: sync message with test

---
 packages/serve/src/index.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/serve/src/index.ts b/packages/serve/src/index.ts
index fdab886157e..558f738f772 100644
--- a/packages/serve/src/index.ts
+++ b/packages/serve/src/index.ts
@@ -32,7 +32,7 @@ export default function serve(): void {
     });
 
     if (webpackArgs.args.length > 0) {
-        process.stderr.write(`Unknown argument: ${webpackArgs.args}`);
+        process.stderr.write(`Unknown option: ${webpackArgs.args}`);
         return;
     }
 

From 7cf46bf478202c477bd435effc1d5b55d949c9f1 Mon Sep 17 00:00:00 2001
From: Kirill Nagaitsev <knagaitsev1@gmail.com>
Date: Fri, 17 Apr 2020 13:07:44 -0500
Subject: [PATCH 16/43] chore: fix styling

---
 packages/serve/src/index.ts                   | 27 +++++++++----------
 packages/webpack-cli/lib/bootstrap.js         |  5 ++--
 .../webpack-cli/lib/groups/AdvancedGroup.js   |  1 -
 .../webpack-cli/lib/groups/ZeroConfigGroup.js |  2 +-
 packages/webpack-cli/lib/utils/arg-parser.js  |  4 +--
 packages/webpack-cli/lib/utils/helpers.js     |  2 +-
 packages/webpack-cli/lib/webpack-cli.js       |  2 --
 7 files changed, 20 insertions(+), 23 deletions(-)

diff --git a/packages/serve/src/index.ts b/packages/serve/src/index.ts
index 558f738f772..bef8c1f2db8 100644
--- a/packages/serve/src/index.ts
+++ b/packages/serve/src/index.ts
@@ -1,7 +1,7 @@
-import { devServer } from "webpack-dev-server/bin/cli-flags";
-import WebpackCLI from "webpack-cli";
-import startDevServer from "./startDevServer";
-import argsToCamelCase from "./args-to-camel-case";
+import { devServer } from 'webpack-dev-server/bin/cli-flags';
+import WebpackCLI from 'webpack-cli';
+import startDevServer from './startDevServer';
+import argsToCamelCase from './args-to-camel-case';
 
 /**
  *
@@ -11,21 +11,20 @@ import argsToCamelCase from "./args-to-camel-case";
  * @returns {Function} invokes the devServer API
  */
 export default function serve(): void {
-	const cli = new WebpackCLI();
-	const core = cli.getCoreFlags();
+    const cli = new WebpackCLI();
+    const core = cli.getCoreFlags();
 
-    const filteredArgs = process.argv.filter(arg => (arg != "serve"));
+    const filteredArgs = process.argv.filter((arg) => arg != 'serve');
     const devServerArgs = cli.argParser(devServer, filteredArgs);
-	const webpackArgs = cli.argParser(core, filteredArgs, process.title, cli.runHelp, cli.runVersion);
+    const webpackArgs = cli.argParser(core, filteredArgs, process.title, cli.runHelp, cli.runVersion);
     const finalArgs = argsToCamelCase(devServerArgs.opts() || {});
 
-
     // pass along the 'hot' argument to the dev server if it exists
-	if (webpackArgs && webpackArgs.opts() && webpackArgs.opts().hot !== undefined) {
+    if (webpackArgs && webpackArgs.opts() && webpackArgs.opts().hot !== undefined) {
         finalArgs['hot'] = webpackArgs.opts().hot;
     }
 
-    Object.keys(finalArgs).forEach(arg => {
+    Object.keys(finalArgs).forEach((arg) => {
         if (finalArgs[arg] === undefined) {
             delete finalArgs[arg];
         }
@@ -36,7 +35,7 @@ export default function serve(): void {
         return;
     }
 
-	cli.getCompiler(webpackArgs.opts(), core).then((compiler): void => {
-		startDevServer(compiler, finalArgs);
-	});
+    cli.getCompiler(webpackArgs.opts(), core).then((compiler): void => {
+        startDevServer(compiler, finalArgs);
+    });
 }
diff --git a/packages/webpack-cli/lib/bootstrap.js b/packages/webpack-cli/lib/bootstrap.js
index 8cc20b168d2..269348e13be 100644
--- a/packages/webpack-cli/lib/bootstrap.js
+++ b/packages/webpack-cli/lib/bootstrap.js
@@ -7,7 +7,7 @@ require('./utils/process-log');
 
 process.title = 'webpack-cli';
 
-const isFlagPresent = (args, flag) => args.find((arg) => [flag, `--${flag}`].includes(arg));
+// const isFlagPresent = (args, flag) => args.find((arg) => [flag, `--${flag}`].includes(arg));
 const isArgCommandName = (arg, cmd) => arg === cmd.name || arg === cmd.alias;
 const removeCmdFromArgs = (args, cmd) => args.filter((arg) => !isArgCommandName(arg, cmd));
 const normalizeFlags = (args, cmd) => {
@@ -43,6 +43,7 @@ const resolveNegatedArgs = (args) => {
 };
 
 async function runCLI(cli, commandIsUsed) {
+    let args;
     const parsedArgs = argParser(core, process.argv, process.title, cli.runHelp, cli.runVersion);
 
     if (parsedArgs.args.includes('help')) {
@@ -98,7 +99,7 @@ async function runCLI(cli, commandIsUsed) {
                 const newArgKeys = Object.keys(argsMap).filter((arg) => !keysToDelete.includes(argsMap[arg].pos));
                 // eslint-disable-next-line require-atomic-updates
                 process.argv = newArgKeys;
-                args = argParser("", core, process.argv);
+                args = argParser('', core, process.argv);
                 await cli.run(args.opts(), core);
                 process.stdout.write('\n');
                 logger.warn('Duplicate flags found, defaulting to last set value');
diff --git a/packages/webpack-cli/lib/groups/AdvancedGroup.js b/packages/webpack-cli/lib/groups/AdvancedGroup.js
index 98dea3e4e4b..dcedc86bf4c 100644
--- a/packages/webpack-cli/lib/groups/AdvancedGroup.js
+++ b/packages/webpack-cli/lib/groups/AdvancedGroup.js
@@ -1,5 +1,4 @@
 const GroupHelper = require('../utils/GroupHelper');
-const logger = require('../utils/logger');
 
 class AdvancedGroup extends GroupHelper {
     constructor(options) {
diff --git a/packages/webpack-cli/lib/groups/ZeroConfigGroup.js b/packages/webpack-cli/lib/groups/ZeroConfigGroup.js
index 0d62ccb62bb..33e96f75916 100644
--- a/packages/webpack-cli/lib/groups/ZeroConfigGroup.js
+++ b/packages/webpack-cli/lib/groups/ZeroConfigGroup.js
@@ -20,7 +20,7 @@ class ZeroConfigGroup extends GroupHelper {
         if (process.env.NODE_ENV && (process.env.NODE_ENV === PRODUCTION || process.env.NODE_ENV === DEVELOPMENT)) {
             return process.env.NODE_ENV;
         } else {
-            if ((this.args.mode !== undefined ) && (this.args.dev || this.args.prod)) {
+            if (this.args.mode !== undefined && (this.args.dev || this.args.prod)) {
                 logger.warn(
                     `You provided both ${this.args.mode ? 'mode' : 'no-mode'} and ${
                         this.args.prod ? '--prod' : '--dev'
diff --git a/packages/webpack-cli/lib/utils/arg-parser.js b/packages/webpack-cli/lib/utils/arg-parser.js
index 4fa97f4133a..03268e2a42f 100644
--- a/packages/webpack-cli/lib/utils/arg-parser.js
+++ b/packages/webpack-cli/lib/utils/arg-parser.js
@@ -1,4 +1,4 @@
-const commander = require("commander");
+const commander = require('commander');
 
 /**
  *  Creates Argument parser corresponding to the supplied options
@@ -7,7 +7,7 @@ const commander = require("commander");
  * @param {object[]} options Array of objects with details about flags
  * @param {string[]} args process.argv or it's subset
  */
-function argParser(options, args, name = "", helpFunction = undefined, versionFunction = undefined) {
+function argParser(options, args, name = '', helpFunction = undefined, versionFunction = undefined) {
     const parser = new commander.Command();
     // Set parser name
     parser.name(name);
diff --git a/packages/webpack-cli/lib/utils/helpers.js b/packages/webpack-cli/lib/utils/helpers.js
index 34fdd0a55d4..4a3fd9f3382 100644
--- a/packages/webpack-cli/lib/utils/helpers.js
+++ b/packages/webpack-cli/lib/utils/helpers.js
@@ -4,7 +4,7 @@
  * @returns {string} output string in kebab-case
  */
 function toKebabCase(str) {
-    return str.replace(/([a-z0-9])([A-Z])/g, '$1-$2').toLowerCase()
+    return str.replace(/([a-z0-9])([A-Z])/g, '$1-$2').toLowerCase();
 }
 
 module.exports = { toKebabCase };
diff --git a/packages/webpack-cli/lib/webpack-cli.js b/packages/webpack-cli/lib/webpack-cli.js
index 078b550bbf8..a141e82ddbd 100644
--- a/packages/webpack-cli/lib/webpack-cli.js
+++ b/packages/webpack-cli/lib/webpack-cli.js
@@ -90,12 +90,10 @@ class WebpackCLI extends GroupHelper {
         return argParser(...args);
     }
 
-
     getCoreFlags() {
         return core;
     }
 
-
     /**
      * Based on the parsed keys, the function will import and create
      * a group that handles respective values

From 231f1818e80858ebf9313003cfe8232272880749 Mon Sep 17 00:00:00 2001
From: Kirill Nagaitsev <knagaitsev1@gmail.com>
Date: Fri, 17 Apr 2020 22:54:13 -0500
Subject: [PATCH 17/43] chore: fix problem with no mode flag

---
 packages/webpack-cli/lib/utils/cli-flags.js | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/packages/webpack-cli/lib/utils/cli-flags.js b/packages/webpack-cli/lib/utils/cli-flags.js
index e6cc3012aaa..b552db2ccd0 100644
--- a/packages/webpack-cli/lib/utils/cli-flags.js
+++ b/packages/webpack-cli/lib/utils/cli-flags.js
@@ -228,14 +228,14 @@ module.exports = {
             description: 'Defines the mode to pass to webpack',
             link: 'https://webpack.js.org/concepts/#mode',
         },
-        {
-            name: 'no-mode',
-            usage: '--no-mode',
-            type: Boolean,
-            group: ZERO_CONFIG_GROUP,
-            description: 'Sets mode="none" which disables any default behavior',
-            link: 'https://webpack.js.org/concepts/#mode',
-        },
+        // {
+        //     name: 'no-mode',
+        //     usage: '--no-mode',
+        //     type: Boolean,
+        //     group: ZERO_CONFIG_GROUP,
+        //     description: 'Sets mode="none" which disables any default behavior',
+        //     link: 'https://webpack.js.org/concepts/#mode',
+        // },
         {
             name: 'version',
             usage: '--version | --version <external-package>',

From 0e1db3bbd500bb80b46ca71a53c9c765cf9d6e6f Mon Sep 17 00:00:00 2001
From: Kirill Nagaitsev <knagaitsev1@gmail.com>
Date: Sat, 18 Apr 2020 01:39:24 -0500
Subject: [PATCH 18/43] chore: started adding info parsing

---
 packages/info/src/index.ts   | 2 +-
 packages/info/src/options.ts | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/packages/info/src/index.ts b/packages/info/src/index.ts
index 10fbafeeb6d..4c282068855 100644
--- a/packages/info/src/index.ts
+++ b/packages/info/src/index.ts
@@ -32,7 +32,7 @@ const DEFAULT_DETAILS: Information = {
 
 export default async function info(...args): Promise<string[]> {
     const cli = new WebpackCLI();
-    const infoArgs = cli.commandLineArgs(options, { argv: args, stopAtFirstUnknown: false });
+    const infoArgs = cli.argParser(options, args).opts();
     const envinfoConfig = {};
 
     if (infoArgs._unknown && infoArgs._unknown.length > 0) {
diff --git a/packages/info/src/options.ts b/packages/info/src/options.ts
index 68bae2e8063..ccfe315e1b4 100644
--- a/packages/info/src/options.ts
+++ b/packages/info/src/options.ts
@@ -1,6 +1,7 @@
 export default [
     {
         name: 'output',
+        usage: '--output <json | markdown>',
         type: String,
         description: 'To get the output in specified format (accept json or markdown)',
     },

From 24cbc8510883524835f703f7106cb58aca8574a3 Mon Sep 17 00:00:00 2001
From: Kirill Nagaitsev <knagaitsev1@gmail.com>
Date: Sat, 18 Apr 2020 11:03:34 -0500
Subject: [PATCH 19/43] chore: parsing without first few parts of process argv

---
 packages/info/src/index.ts                   |  2 +-
 packages/serve/src/index.ts                  |  5 +++--
 packages/webpack-cli/lib/bootstrap.js        |  2 +-
 packages/webpack-cli/lib/utils/arg-parser.js | 15 ++++++++++++---
 4 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/packages/info/src/index.ts b/packages/info/src/index.ts
index 4c282068855..383911bf538 100644
--- a/packages/info/src/index.ts
+++ b/packages/info/src/index.ts
@@ -32,7 +32,7 @@ const DEFAULT_DETAILS: Information = {
 
 export default async function info(...args): Promise<string[]> {
     const cli = new WebpackCLI();
-    const infoArgs = cli.argParser(options, args).opts();
+    const infoArgs = cli.argParser(options, args, true).opts();
     const envinfoConfig = {};
 
     if (infoArgs._unknown && infoArgs._unknown.length > 0) {
diff --git a/packages/serve/src/index.ts b/packages/serve/src/index.ts
index bef8c1f2db8..21906435de5 100644
--- a/packages/serve/src/index.ts
+++ b/packages/serve/src/index.ts
@@ -15,8 +15,9 @@ export default function serve(): void {
     const core = cli.getCoreFlags();
 
     const filteredArgs = process.argv.filter((arg) => arg != 'serve');
-    const devServerArgs = cli.argParser(devServer, filteredArgs);
-    const webpackArgs = cli.argParser(core, filteredArgs, process.title, cli.runHelp, cli.runVersion);
+    const parsedDevServerArgs = cli.argParser(devServer, filteredArgs);
+    const devServerArgs = parsedDevServerArgs.opts();
+    const webpackArgs = cli.argParser(core, filteredArgs, false, process.title, cli.runHelp, cli.runVersion);
     const finalArgs = argsToCamelCase(devServerArgs.opts() || {});
 
     // pass along the 'hot' argument to the dev server if it exists
diff --git a/packages/webpack-cli/lib/bootstrap.js b/packages/webpack-cli/lib/bootstrap.js
index 269348e13be..cc66f1c7cab 100644
--- a/packages/webpack-cli/lib/bootstrap.js
+++ b/packages/webpack-cli/lib/bootstrap.js
@@ -44,7 +44,7 @@ const resolveNegatedArgs = (args) => {
 
 async function runCLI(cli, commandIsUsed) {
     let args;
-    const parsedArgs = argParser(core, process.argv, process.title, cli.runHelp, cli.runVersion);
+    const parsedArgs = argParser(core, process.argv, false, process.title, cli.runHelp, cli.runVersion);
 
     if (parsedArgs.args.includes('help')) {
         cli.runHelp(process.argv);
diff --git a/packages/webpack-cli/lib/utils/arg-parser.js b/packages/webpack-cli/lib/utils/arg-parser.js
index 03268e2a42f..360275eca86 100644
--- a/packages/webpack-cli/lib/utils/arg-parser.js
+++ b/packages/webpack-cli/lib/utils/arg-parser.js
@@ -6,8 +6,10 @@ const commander = require('commander');
  *
  * @param {object[]} options Array of objects with details about flags
  * @param {string[]} args process.argv or it's subset
+ * @param {boolean} argsOnly false if all of process.argv has been provided, true if
+ * args is only a subset of process.argv that removes the first couple elements
  */
-function argParser(options, args, name = '', helpFunction = undefined, versionFunction = undefined) {
+function argParser(options, args, argsOnly = false, name = '', helpFunction = undefined, versionFunction = undefined) {
     const parser = new commander.Command();
     // Set parser name
     parser.name(name);
@@ -34,12 +36,19 @@ function argParser(options, args, name = '', helpFunction = undefined, versionFu
     // Register options on the parser
     options.reduce((parserInstance, option) => {
         const flags = option.alias ? `-${option.alias}, --${option.name}` : `--${option.name}`;
-        const flagsWithType = option.type !== Boolean ? flags + ' [type]' : flags;
+        const flagsWithType = option.type !== Boolean ? flags + ' <type>' : flags;
         parserInstance.option(flagsWithType, option.description, option.defaultValue);
         return parserInstance;
     }, parser);
 
-    return parser.parse(args);
+    // if we are parsing a subset of process.argv that includes
+    // only the arguments themselves (e.g. ['--option', 'value'])
+    // then we need from: 'user' passed into commander parse
+    // otherwise we are parsing a full process.argv
+    // (e.g. ['node', '/path/to/...', '--option', 'value'])
+    const parseOptions = argsOnly ? { from: 'user' } : {};
+
+    return parser.parse(args, parseOptions);
 }
 
 module.exports = argParser;

From cbbed324ec4e23d1d86fd699c80e80b5409331c4 Mon Sep 17 00:00:00 2001
From: Kirill Nagaitsev <knagaitsev1@gmail.com>
Date: Sat, 18 Apr 2020 11:06:28 -0500
Subject: [PATCH 20/43] chore: fixed args calling in serve

---
 packages/serve/src/index.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/serve/src/index.ts b/packages/serve/src/index.ts
index 21906435de5..5a8db876274 100644
--- a/packages/serve/src/index.ts
+++ b/packages/serve/src/index.ts
@@ -18,7 +18,7 @@ export default function serve(): void {
     const parsedDevServerArgs = cli.argParser(devServer, filteredArgs);
     const devServerArgs = parsedDevServerArgs.opts();
     const webpackArgs = cli.argParser(core, filteredArgs, false, process.title, cli.runHelp, cli.runVersion);
-    const finalArgs = argsToCamelCase(devServerArgs.opts() || {});
+    const finalArgs = argsToCamelCase(devServerArgs || {});
 
     // pass along the 'hot' argument to the dev server if it exists
     if (webpackArgs && webpackArgs.opts() && webpackArgs.opts().hot !== undefined) {

From edf38f288e154013753b3f83f960526329e1b8d9 Mon Sep 17 00:00:00 2001
From: Kirill Nagaitsev <knagaitsev1@gmail.com>
Date: Sat, 18 Apr 2020 11:11:53 -0500
Subject: [PATCH 21/43] chore: fixing serve

---
 packages/serve/src/index.ts | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/packages/serve/src/index.ts b/packages/serve/src/index.ts
index 5a8db876274..9de85614335 100644
--- a/packages/serve/src/index.ts
+++ b/packages/serve/src/index.ts
@@ -17,12 +17,13 @@ export default function serve(): void {
     const filteredArgs = process.argv.filter((arg) => arg != 'serve');
     const parsedDevServerArgs = cli.argParser(devServer, filteredArgs);
     const devServerArgs = parsedDevServerArgs.opts();
-    const webpackArgs = cli.argParser(core, filteredArgs, false, process.title, cli.runHelp, cli.runVersion);
+    const parsedWebpackArgs = cli.argParser(core, parsedDevServerArgs.args, true, process.title, cli.runHelp, cli.runVersion);
+    const webpackArgs = parsedWebpackArgs.opts();
     const finalArgs = argsToCamelCase(devServerArgs || {});
 
     // pass along the 'hot' argument to the dev server if it exists
-    if (webpackArgs && webpackArgs.opts() && webpackArgs.opts().hot !== undefined) {
-        finalArgs['hot'] = webpackArgs.opts().hot;
+    if (webpackArgs && webpackArgs.hot !== undefined) {
+        finalArgs['hot'] = webpackArgs.hot;
     }
 
     Object.keys(finalArgs).forEach((arg) => {
@@ -31,12 +32,12 @@ export default function serve(): void {
         }
     });
 
-    if (webpackArgs.args.length > 0) {
-        process.stderr.write(`Unknown option: ${webpackArgs.args}`);
+    if (parsedWebpackArgs.args.length > 0) {
+        process.stderr.write(`Unknown option: ${parsedWebpackArgs.args}\n`);
         return;
     }
 
-    cli.getCompiler(webpackArgs.opts(), core).then((compiler): void => {
+    cli.getCompiler(webpackArgs, core).then((compiler): void => {
         startDevServer(compiler, finalArgs);
     });
 }

From a7fa0908093a3d1cfc97ffe98d9ab6370b90e993 Mon Sep 17 00:00:00 2001
From: Kirill Nagaitsev <knagaitsev1@gmail.com>
Date: Sat, 18 Apr 2020 13:51:42 -0500
Subject: [PATCH 22/43] chore: fix no-mode tests

---
 packages/webpack-cli/lib/bootstrap.js          |  3 ++-
 .../webpack-cli/lib/groups/ZeroConfigGroup.js  |  6 ++++--
 packages/webpack-cli/lib/utils/cli-flags.js    | 18 +++++++++---------
 test/no-mode/no-mode.test.js                   |  8 +++++---
 4 files changed, 20 insertions(+), 15 deletions(-)

diff --git a/packages/webpack-cli/lib/bootstrap.js b/packages/webpack-cli/lib/bootstrap.js
index cc66f1c7cab..7b28697f038 100644
--- a/packages/webpack-cli/lib/bootstrap.js
+++ b/packages/webpack-cli/lib/bootstrap.js
@@ -72,7 +72,8 @@ async function runCLI(cli, commandIsUsed) {
                 cliExecuter();
                 return;
             }
-            const result = await cli.run(parsedArgs.opts(), core);
+            const parsedArgsOpts = parsedArgs.opts();
+            const result = await cli.run(parsedArgsOpts, core);
             if (!result) {
                 return;
             }
diff --git a/packages/webpack-cli/lib/groups/ZeroConfigGroup.js b/packages/webpack-cli/lib/groups/ZeroConfigGroup.js
index 33e96f75916..7259a4e835b 100644
--- a/packages/webpack-cli/lib/groups/ZeroConfigGroup.js
+++ b/packages/webpack-cli/lib/groups/ZeroConfigGroup.js
@@ -20,7 +20,9 @@ class ZeroConfigGroup extends GroupHelper {
         if (process.env.NODE_ENV && (process.env.NODE_ENV === PRODUCTION || process.env.NODE_ENV === DEVELOPMENT)) {
             return process.env.NODE_ENV;
         } else {
-            if (this.args.mode !== undefined && (this.args.dev || this.args.prod)) {
+            // commander sets mode to false if --no-mode is specified
+            const noMode = this.args.mode === false;
+            if ((this.args.mode || noMode) && (this.args.dev || this.args.prod)) {
                 logger.warn(
                     `You provided both ${this.args.mode ? 'mode' : 'no-mode'} and ${
                         this.args.prod ? '--prod' : '--dev'
@@ -44,7 +46,7 @@ class ZeroConfigGroup extends GroupHelper {
                 return PRODUCTION;
             } else if (this.args.dev) {
                 return DEVELOPMENT;
-            } else if (this.args.noMode) {
+            } else if (noMode) {
                 return NONE;
             }
             return PRODUCTION;
diff --git a/packages/webpack-cli/lib/utils/cli-flags.js b/packages/webpack-cli/lib/utils/cli-flags.js
index b552db2ccd0..def246fe544 100644
--- a/packages/webpack-cli/lib/utils/cli-flags.js
+++ b/packages/webpack-cli/lib/utils/cli-flags.js
@@ -222,20 +222,20 @@ module.exports = {
         },
         {
             name: 'mode',
-            usage: '--mode <development | production>',
+            usage: '--mode <development | production | none>',
             type: String,
             group: ZERO_CONFIG_GROUP,
             description: 'Defines the mode to pass to webpack',
             link: 'https://webpack.js.org/concepts/#mode',
         },
-        // {
-        //     name: 'no-mode',
-        //     usage: '--no-mode',
-        //     type: Boolean,
-        //     group: ZERO_CONFIG_GROUP,
-        //     description: 'Sets mode="none" which disables any default behavior',
-        //     link: 'https://webpack.js.org/concepts/#mode',
-        // },
+        {
+            name: 'no-mode',
+            usage: '--no-mode',
+            type: Boolean,
+            group: ZERO_CONFIG_GROUP,
+            description: 'Sets mode="none" which disables any default behavior',
+            link: 'https://webpack.js.org/concepts/#mode',
+        },
         {
             name: 'version',
             usage: '--version | --version <external-package>',
diff --git a/test/no-mode/no-mode.test.js b/test/no-mode/no-mode.test.js
index aa71c614dfe..f2f743d2661 100644
--- a/test/no-mode/no-mode.test.js
+++ b/test/no-mode/no-mode.test.js
@@ -38,10 +38,11 @@ describe('no-mode flag', () => {
         });
     });
 
-    it('should load a production config when --mode=production & --no-mode are passed', (done) => {
+    it('should load a none config when --mode=production is passed before --no-mode', (done) => {
         const { stderr, stdout } = run(__dirname, ['--mode', 'production', '--no-mode']);
         expect(stderr).toBeFalsy();
         expect(stdout).toBeTruthy();
+        expect(stdout).not.toContain('main.js.map');
 
         stat(resolve(__dirname, './bin/main.js'), (err, stats) => {
             expect(err).toBe(null);
@@ -50,10 +51,11 @@ describe('no-mode flag', () => {
         });
     });
 
-    it('should load a development config when --mode=development and --no-mode are passed', (done) => {
-        const { stderr, stdout } = run(__dirname, ['--mode', 'development', '--no-mode']);
+    it('should load a none config when --mode=production is passed after --no-mode', (done) => {
+        const { stderr, stdout } = run(__dirname, ['--no-mode', '--mode', 'production']);
         expect(stderr).toBeFalsy();
         expect(stdout).toBeTruthy();
+        expect(stdout).toContain('main.js.map');
 
         stat(resolve(__dirname, './bin/main.js'), (err, stats) => {
             expect(err).toBe(null);

From ab8e885386390fa18a6fb3970e1ca5364f313a63 Mon Sep 17 00:00:00 2001
From: Kirill Nagaitsev <knagaitsev1@gmail.com>
Date: Sat, 18 Apr 2020 14:52:56 -0500
Subject: [PATCH 23/43] chore: fix output defaults tests

---
 packages/webpack-cli/lib/utils/arg-parser.js |  2 +-
 test/defaults/output-defaults.test.js        | 21 +++++++++++++-------
 2 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/packages/webpack-cli/lib/utils/arg-parser.js b/packages/webpack-cli/lib/utils/arg-parser.js
index 360275eca86..16fa5baf4e1 100644
--- a/packages/webpack-cli/lib/utils/arg-parser.js
+++ b/packages/webpack-cli/lib/utils/arg-parser.js
@@ -36,7 +36,7 @@ function argParser(options, args, argsOnly = false, name = '', helpFunction = un
     // Register options on the parser
     options.reduce((parserInstance, option) => {
         const flags = option.alias ? `-${option.alias}, --${option.name}` : `--${option.name}`;
-        const flagsWithType = option.type !== Boolean ? flags + ' <type>' : flags;
+        const flagsWithType = option.type !== Boolean ? flags + ' <value>' : flags;
         parserInstance.option(flagsWithType, option.description, option.defaultValue);
         return parserInstance;
     }, parser);
diff --git a/test/defaults/output-defaults.test.js b/test/defaults/output-defaults.test.js
index 947c4ba2366..8e04eb511ee 100644
--- a/test/defaults/output-defaults.test.js
+++ b/test/defaults/output-defaults.test.js
@@ -5,18 +5,18 @@ const { run } = require('../utils/test-utils');
 
 describe('output flag defaults', () => {
     it('should create default file for a given directory', (done) => {
-        run(__dirname, ['--entry', './a.js', '--output', './binary'], false);
-
+        const { stdout } = run(__dirname, ['--entry', './a.js', '--output', './binary'], false);
+        // Should print a warning about config fallback since we did not supply --defaults
+        expect(stdout).toContain('option has not been set, webpack will fallback to');
         stat(resolve(__dirname, './binary/main.js'), (err, stats) => {
             expect(err).toBe(null);
             expect(stats.isFile()).toBe(true);
             done();
         });
     });
-    it('set default output directory on empty flag', (done) => {
-        const { stdout } = run(__dirname, ['--entry', './a.js', '--output'], false);
-        // Should print a warning about config fallback since we did not supply --defaults
-        expect(stdout).toContain('option has not been set, webpack will fallback to');
+
+    it('set default output directory on no output flag', (done) => {
+        run(__dirname, ['--entry', './a.js'], false);
 
         stat(resolve(__dirname, './dist/main.js'), (err, stats) => {
             expect(err).toBe(null);
@@ -24,9 +24,16 @@ describe('output flag defaults', () => {
             done();
         });
     });
+
+    it('throw error on empty output flag', () => {
+        const { stderr } = run(__dirname, ['--entry', './a.js', '--output'], false);
+        expect(stderr).toContain("error: option '-o, --output <value>' argument missing");
+    });
+
     it('should not throw when --defaults flag is passed', (done) => {
-        const { stderr } = run(__dirname, ['--defaults'], false);
+        const { stdout, stderr } = run(__dirname, ['--defaults'], false);
         // When using --defaults it should not print warnings about config fallback
+        expect(stdout).not.toContain('option has not been set, webpack will fallback to');
         expect(stderr).toBeFalsy();
         stat(resolve(__dirname, './dist/main.js'), (err, stats) => {
             expect(err).toBe(null);

From c4a4d6959fdbacbe5519b3a06f5e143e8b522f08 Mon Sep 17 00:00:00 2001
From: Kirill Nagaitsev <knagaitsev1@gmail.com>
Date: Sat, 18 Apr 2020 15:06:40 -0500
Subject: [PATCH 24/43] chore: handle default webpack entry arg

---
 packages/webpack-cli/lib/bootstrap.js | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/packages/webpack-cli/lib/bootstrap.js b/packages/webpack-cli/lib/bootstrap.js
index 7b28697f038..a5943ca597c 100644
--- a/packages/webpack-cli/lib/bootstrap.js
+++ b/packages/webpack-cli/lib/bootstrap.js
@@ -62,7 +62,7 @@ async function runCLI(cli, commandIsUsed) {
         return await cli.runCommand(commandIsUsed, ...args);
     } else {
         try {
-            if (parsedArgs.args.length > 0) {
+            if (parsedArgs.args.length > 1) {
                 resolveNegatedArgs(parsedArgs.args);
                 parsedArgs.args
                     .filter((e) => e)
@@ -73,6 +73,12 @@ async function runCLI(cli, commandIsUsed) {
                 return;
             }
             const parsedArgsOpts = parsedArgs.opts();
+            // handle the default webpack entry CLI argument, where instead
+            // of doing 'webpack-cli --entry ./index.js' you can simply do
+            // 'webpack-cli ./index.js'
+            if (parsedArgs.args.length === 1) {
+                parsedArgsOpts.entry = parsedArgs.args[0];
+            }
             const result = await cli.run(parsedArgsOpts, core);
             if (!result) {
                 return;

From 4eccb84168c15439b2dfe22fecd4b03100a86cd5 Mon Sep 17 00:00:00 2001
From: Kirill Nagaitsev <knagaitsev1@gmail.com>
Date: Sat, 18 Apr 2020 15:14:29 -0500
Subject: [PATCH 25/43] chore: fix basic config test

---
 test/config/basic/basic-config.test.js | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/test/config/basic/basic-config.test.js b/test/config/basic/basic-config.test.js
index dec2eef82bb..01feb8afb94 100644
--- a/test/config/basic/basic-config.test.js
+++ b/test/config/basic/basic-config.test.js
@@ -5,7 +5,11 @@ const { run } = require('../../utils/test-utils');
 
 describe('basic config file', () => {
     it('is able to understand and parse a very basic configuration file', (done) => {
-        const { stdout, stderr } = run(__dirname, ['-c', resolve(__dirname, 'webpack.config.js'), '--output', './binary/a.bundle.js']);
+        const { stdout, stderr } = run(
+            __dirname,
+            ['-c', resolve(__dirname, 'webpack.config.js'), '--output', './binary/a.bundle.js'],
+            false,
+        );
         expect(stderr).toBeFalsy();
         expect(stdout).not.toBe(undefined);
         stat(resolve(__dirname, './binary/a.bundle.js'), (err, stats) => {

From 26c65ccfd8ba43ce7f5944805066c9223a507085 Mon Sep 17 00:00:00 2001
From: Kirill Nagaitsev <knagaitsev1@gmail.com>
Date: Sat, 18 Apr 2020 15:29:53 -0500
Subject: [PATCH 26/43] chore: fix version and help commands

---
 packages/serve/src/index.ts                  |  2 +-
 packages/webpack-cli/lib/bootstrap.js        | 15 ++++-----------
 packages/webpack-cli/lib/utils/arg-parser.js |  2 +-
 3 files changed, 6 insertions(+), 13 deletions(-)

diff --git a/packages/serve/src/index.ts b/packages/serve/src/index.ts
index 9de85614335..44fc9a5c24d 100644
--- a/packages/serve/src/index.ts
+++ b/packages/serve/src/index.ts
@@ -17,7 +17,7 @@ export default function serve(): void {
     const filteredArgs = process.argv.filter((arg) => arg != 'serve');
     const parsedDevServerArgs = cli.argParser(devServer, filteredArgs);
     const devServerArgs = parsedDevServerArgs.opts();
-    const parsedWebpackArgs = cli.argParser(core, parsedDevServerArgs.args, true, process.title, cli.runHelp, cli.runVersion);
+    const parsedWebpackArgs = cli.argParser(core, parsedDevServerArgs.args, true, process.title);
     const webpackArgs = parsedWebpackArgs.opts();
     const finalArgs = argsToCamelCase(devServerArgs || {});
 
diff --git a/packages/webpack-cli/lib/bootstrap.js b/packages/webpack-cli/lib/bootstrap.js
index a5943ca597c..78ca0cc9270 100644
--- a/packages/webpack-cli/lib/bootstrap.js
+++ b/packages/webpack-cli/lib/bootstrap.js
@@ -44,17 +44,10 @@ const resolveNegatedArgs = (args) => {
 
 async function runCLI(cli, commandIsUsed) {
     let args;
-    const parsedArgs = argParser(core, process.argv, false, process.title, cli.runHelp, cli.runVersion);
-
-    if (parsedArgs.args.includes('help')) {
-        cli.runHelp(process.argv);
-        process.exit(0);
-    }
-
-    if (parsedArgs.args.includes('version')) {
-        cli.runVersion();
-        process.exit(0);
-    }
+    const runVersion = () => {
+        cli.runVersion(commandIsUsed);
+    };
+    const parsedArgs = argParser(core, process.argv, false, process.title, cli.runHelp, runVersion);
 
     if (commandIsUsed) {
         commandIsUsed.defaultOption = true;
diff --git a/packages/webpack-cli/lib/utils/arg-parser.js b/packages/webpack-cli/lib/utils/arg-parser.js
index 16fa5baf4e1..6860d5a53de 100644
--- a/packages/webpack-cli/lib/utils/arg-parser.js
+++ b/packages/webpack-cli/lib/utils/arg-parser.js
@@ -17,7 +17,7 @@ function argParser(options, args, argsOnly = false, name = '', helpFunction = un
     // Use customized version output if available
     if (versionFunction) {
         parser.on('option:version', () => {
-            versionFunction(args);
+            versionFunction();
             process.exit(0);
         });
     }

From 783f4563a7ae9b88a8bb059c913e879b6ad2bb3f Mon Sep 17 00:00:00 2001
From: Kirill Nagaitsev <knagaitsev1@gmail.com>
Date: Sat, 18 Apr 2020 15:42:23 -0500
Subject: [PATCH 27/43] chore: change help, version, and fix entry checking

---
 packages/webpack-cli/lib/bootstrap.js | 27 +++++++++++++++++++++------
 1 file changed, 21 insertions(+), 6 deletions(-)

diff --git a/packages/webpack-cli/lib/bootstrap.js b/packages/webpack-cli/lib/bootstrap.js
index 78ca0cc9270..85079f4e898 100644
--- a/packages/webpack-cli/lib/bootstrap.js
+++ b/packages/webpack-cli/lib/bootstrap.js
@@ -49,13 +49,31 @@ async function runCLI(cli, commandIsUsed) {
     };
     const parsedArgs = argParser(core, process.argv, false, process.title, cli.runHelp, runVersion);
 
+    if (parsedArgs.args.includes('help')) {
+        cli.runHelp(process.argv);
+        process.exit(0);
+    }
+
+    if (parsedArgs.args.includes('version')) {
+        runVersion();
+        process.exit(0);
+    }
+
     if (commandIsUsed) {
         commandIsUsed.defaultOption = true;
         args = normalizeFlags(process.argv, commandIsUsed);
         return await cli.runCommand(commandIsUsed, ...args);
     } else {
         try {
-            if (parsedArgs.args.length > 1) {
+            // handle the default webpack entry CLI argument, where instead
+            // of doing 'webpack-cli --entry ./index.js' you can simply do
+            // 'webpack-cli ./index.js'
+            // if the unknown arg starts with a '-', it will be considered
+            // an unknown flag rather than an entry
+            let entry;
+            if (parsedArgs.args.length === 1 && !parsedArgs.args[0].startsWith('-')) {
+                entry = parsedArgs.args[0];
+            } else if (parsedArgs.args.length > 0) {
                 resolveNegatedArgs(parsedArgs.args);
                 parsedArgs.args
                     .filter((e) => e)
@@ -66,11 +84,8 @@ async function runCLI(cli, commandIsUsed) {
                 return;
             }
             const parsedArgsOpts = parsedArgs.opts();
-            // handle the default webpack entry CLI argument, where instead
-            // of doing 'webpack-cli --entry ./index.js' you can simply do
-            // 'webpack-cli ./index.js'
-            if (parsedArgs.args.length === 1) {
-                parsedArgsOpts.entry = parsedArgs.args[0];
+            if (entry) {
+                parsedArgsOpts.entry = entry;
             }
             const result = await cli.run(parsedArgsOpts, core);
             if (!result) {

From 29aa5c026bfdbc21618992c3034e14173f14a778 Mon Sep 17 00:00:00 2001
From: Kirill Nagaitsev <knagaitsev1@gmail.com>
Date: Thu, 23 Apr 2020 01:47:53 -0500
Subject: [PATCH 28/43] chore: add some negated flag handling

---
 packages/info/src/index.ts                   |  2 +-
 packages/serve/src/index.ts                  | 15 +++++---
 packages/webpack-cli/lib/bootstrap.js        | 39 ++++----------------
 packages/webpack-cli/lib/utils/arg-parser.js | 38 ++++++++++++++++++-
 test/no-mode/no-mode.test.js                 |  8 +++-
 5 files changed, 62 insertions(+), 40 deletions(-)

diff --git a/packages/info/src/index.ts b/packages/info/src/index.ts
index 383911bf538..d62b6a3353a 100644
--- a/packages/info/src/index.ts
+++ b/packages/info/src/index.ts
@@ -32,7 +32,7 @@ const DEFAULT_DETAILS: Information = {
 
 export default async function info(...args): Promise<string[]> {
     const cli = new WebpackCLI();
-    const infoArgs = cli.argParser(options, args, true).opts();
+    const infoArgs = cli.argParser(options, args, true).opts;
     const envinfoConfig = {};
 
     if (infoArgs._unknown && infoArgs._unknown.length > 0) {
diff --git a/packages/serve/src/index.ts b/packages/serve/src/index.ts
index 44fc9a5c24d..77ed62ab807 100644
--- a/packages/serve/src/index.ts
+++ b/packages/serve/src/index.ts
@@ -1,5 +1,6 @@
 import { devServer } from 'webpack-dev-server/bin/cli-flags';
 import WebpackCLI from 'webpack-cli';
+import logger from 'webpack-cli/lib/utils/logger';
 import startDevServer from './startDevServer';
 import argsToCamelCase from './args-to-camel-case';
 
@@ -16,9 +17,9 @@ export default function serve(): void {
 
     const filteredArgs = process.argv.filter((arg) => arg != 'serve');
     const parsedDevServerArgs = cli.argParser(devServer, filteredArgs);
-    const devServerArgs = parsedDevServerArgs.opts();
-    const parsedWebpackArgs = cli.argParser(core, parsedDevServerArgs.args, true, process.title);
-    const webpackArgs = parsedWebpackArgs.opts();
+    const devServerArgs = parsedDevServerArgs.opts;
+    const parsedWebpackArgs = cli.argParser(core, parsedDevServerArgs.unknownArgs, true, process.title);
+    const webpackArgs = parsedWebpackArgs.opts;
     const finalArgs = argsToCamelCase(devServerArgs || {});
 
     // pass along the 'hot' argument to the dev server if it exists
@@ -32,8 +33,12 @@ export default function serve(): void {
         }
     });
 
-    if (parsedWebpackArgs.args.length > 0) {
-        process.stderr.write(`Unknown option: ${parsedWebpackArgs.args}\n`);
+    if (parsedWebpackArgs.unknownArgs.length > 0) {
+        parsedWebpackArgs.unknownArgs
+            .filter((e) => e)
+            .forEach((unknown) => {
+                logger.warn('Unknown argument:', unknown);
+            });
         return;
     }
 
diff --git a/packages/webpack-cli/lib/bootstrap.js b/packages/webpack-cli/lib/bootstrap.js
index 85079f4e898..860e1fbbeb8 100644
--- a/packages/webpack-cli/lib/bootstrap.js
+++ b/packages/webpack-cli/lib/bootstrap.js
@@ -20,28 +20,6 @@ const isCommandUsed = (commands) =>
         return process.argv.includes(cmd.name) || process.argv.includes(cmd.alias);
     });
 
-const resolveNegatedArgs = (args) => {
-    args.forEach((arg, idx) => {
-        if (arg.includes('--') || arg.includes('--no')) {
-            const argPair = arg.split('=');
-            const optName = arg.includes('--no') ? argPair[0].slice(5) : argPair[0].slice(2);
-
-            let argValue = arg.includes('--no') ? 'false' : argPair[1];
-            if (argValue === 'false') {
-                argValue = false;
-            } else if (argValue === 'true') {
-                argValue = true;
-            }
-            const cliFlag = core.find((opt) => opt.name === optName);
-            if (cliFlag) {
-                args[cliFlag.group][optName] = argValue;
-                args._all[optName] = argValue;
-                args.args[idx] = null;
-            }
-        }
-    });
-};
-
 async function runCLI(cli, commandIsUsed) {
     let args;
     const runVersion = () => {
@@ -49,12 +27,12 @@ async function runCLI(cli, commandIsUsed) {
     };
     const parsedArgs = argParser(core, process.argv, false, process.title, cli.runHelp, runVersion);
 
-    if (parsedArgs.args.includes('help')) {
+    if (parsedArgs.unknownArgs.includes('help')) {
         cli.runHelp(process.argv);
         process.exit(0);
     }
 
-    if (parsedArgs.args.includes('version')) {
+    if (parsedArgs.unknownArgs.includes('version')) {
         runVersion();
         process.exit(0);
     }
@@ -71,11 +49,10 @@ async function runCLI(cli, commandIsUsed) {
             // if the unknown arg starts with a '-', it will be considered
             // an unknown flag rather than an entry
             let entry;
-            if (parsedArgs.args.length === 1 && !parsedArgs.args[0].startsWith('-')) {
-                entry = parsedArgs.args[0];
-            } else if (parsedArgs.args.length > 0) {
-                resolveNegatedArgs(parsedArgs.args);
-                parsedArgs.args
+            if (parsedArgs.unknownArgs.length === 1 && !parsedArgs.unknownArgs[0].startsWith('-')) {
+                entry = parsedArgs.unknownArgs[0];
+            } else if (parsedArgs.unknownArgs.length > 0) {
+                parsedArgs.unknownArgs
                     .filter((e) => e)
                     .forEach((unknown) => {
                         logger.warn('Unknown argument:', unknown);
@@ -83,7 +60,7 @@ async function runCLI(cli, commandIsUsed) {
                 cliExecuter();
                 return;
             }
-            const parsedArgsOpts = parsedArgs.opts();
+            const parsedArgsOpts = parsedArgs.opts;
             if (entry) {
                 parsedArgsOpts.entry = entry;
             }
@@ -115,7 +92,7 @@ async function runCLI(cli, commandIsUsed) {
                 // eslint-disable-next-line require-atomic-updates
                 process.argv = newArgKeys;
                 args = argParser('', core, process.argv);
-                await cli.run(args.opts(), core);
+                await cli.run(args.opts, core);
                 process.stdout.write('\n');
                 logger.warn('Duplicate flags found, defaulting to last set value');
             } else {
diff --git a/packages/webpack-cli/lib/utils/arg-parser.js b/packages/webpack-cli/lib/utils/arg-parser.js
index 6860d5a53de..43bacaa5de1 100644
--- a/packages/webpack-cli/lib/utils/arg-parser.js
+++ b/packages/webpack-cli/lib/utils/arg-parser.js
@@ -1,4 +1,5 @@
 const commander = require('commander');
+const logger = require('./logger');
 
 /**
  *  Creates Argument parser corresponding to the supplied options
@@ -38,6 +39,10 @@ function argParser(options, args, argsOnly = false, name = '', helpFunction = un
         const flags = option.alias ? `-${option.alias}, --${option.name}` : `--${option.name}`;
         const flagsWithType = option.type !== Boolean ? flags + ' <value>' : flags;
         parserInstance.option(flagsWithType, option.description, option.defaultValue);
+        if (option.type === Boolean) {
+            const negatedFlag = `--no-${option.name}`;
+            parserInstance.option(negatedFlag, `negates ${option.name}`);
+        }
         return parserInstance;
     }, parser);
 
@@ -48,7 +53,38 @@ function argParser(options, args, argsOnly = false, name = '', helpFunction = un
     // (e.g. ['node', '/path/to/...', '--option', 'value'])
     const parseOptions = argsOnly ? { from: 'user' } : {};
 
-    return parser.parse(args, parseOptions);
+    const result = parser.parse(args, parseOptions);
+    const opts = result.opts();
+
+    const unknownArgs = result.args;
+
+    args.forEach((arg) => {
+        const flagName = arg.slice(5);
+        const option = options.find((opt) => opt.name === flagName);
+        const flag = `--${flagName}`;
+        const flagUsed = args.includes(flag) && !unknownArgs.includes(flag);
+        let alias = '';
+        let aliasUsed = false;
+        if (option && option.alias) {
+            alias = `-${option.alias}`;
+            aliasUsed = args.includes(alias) && !unknownArgs.includes(alias);
+        }
+
+        // this is a negated flag that is not an unknown flag, but the flag
+        // it is negating was also provided
+        if (arg.startsWith('--no-') && (flagUsed || aliasUsed) && !unknownArgs.includes(arg)) {
+            logger.warn(
+                `You provided both ${
+                    flagUsed ? flag : alias
+                } and ${arg}. We will use only the last of these flags that you provided in your CLI arguments`,
+            );
+        }
+    });
+
+    return {
+        unknownArgs,
+        opts,
+    };
 }
 
 module.exports = argParser;
diff --git a/test/no-mode/no-mode.test.js b/test/no-mode/no-mode.test.js
index f2f743d2661..0ec137128bb 100644
--- a/test/no-mode/no-mode.test.js
+++ b/test/no-mode/no-mode.test.js
@@ -40,7 +40,9 @@ describe('no-mode flag', () => {
 
     it('should load a none config when --mode=production is passed before --no-mode', (done) => {
         const { stderr, stdout } = run(__dirname, ['--mode', 'production', '--no-mode']);
-        expect(stderr).toBeFalsy();
+        expect(stderr).toContain(
+            'You provided both --mode and --no-mode. We will use only the last of these flags that you provided in your CLI arguments',
+        );
         expect(stdout).toBeTruthy();
         expect(stdout).not.toContain('main.js.map');
 
@@ -53,7 +55,9 @@ describe('no-mode flag', () => {
 
     it('should load a none config when --mode=production is passed after --no-mode', (done) => {
         const { stderr, stdout } = run(__dirname, ['--no-mode', '--mode', 'production']);
-        expect(stderr).toBeFalsy();
+        expect(stderr).toContain(
+            'You provided both --mode and --no-mode. We will use only the last of these flags that you provided in your CLI arguments',
+        );
         expect(stdout).toBeTruthy();
         expect(stdout).toContain('main.js.map');
 

From f1888cf72d311b717dd1c8e98f85532a15375d8a Mon Sep 17 00:00:00 2001
From: Kirill Nagaitsev <knagaitsev1@gmail.com>
Date: Thu, 23 Apr 2020 19:50:56 -0500
Subject: [PATCH 29/43] chore: fix serve test

---
 test/serve/basic/serve-basic.test.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/serve/basic/serve-basic.test.js b/test/serve/basic/serve-basic.test.js
index 8fc66398e7c..bb32dfd1846 100644
--- a/test/serve/basic/serve-basic.test.js
+++ b/test/serve/basic/serve-basic.test.js
@@ -48,7 +48,7 @@ describe('basic serve usage', () => {
         it('throws error on unknown flag', async () => {
             const { stdout, stderr } = await runServe(['--port', port, '--unknown-flag'], testPath);
             expect(stdout).toHaveLength(0);
-            expect(stderr).toContain('Unknown option: --unknown-flag');
+            expect(stderr).toContain('Unknown argument: --unknown-flag');
         });
     }
 });

From 793e51e36247d90f2c5c096b99d8b20f0e383bd1 Mon Sep 17 00:00:00 2001
From: Kirill Nagaitsev <knagaitsev1@gmail.com>
Date: Thu, 23 Apr 2020 20:23:31 -0500
Subject: [PATCH 30/43] chore: rename misleading parse-args to parse-node-args

---
 packages/webpack-cli/bin/cli.js                             | 4 ++--
 .../lib/utils/{parse-args.js => parse-node-args.js}         | 0
 test/node/node.test.js                                      | 6 +++---
 3 files changed, 5 insertions(+), 5 deletions(-)
 rename packages/webpack-cli/lib/utils/{parse-args.js => parse-node-args.js} (100%)

diff --git a/packages/webpack-cli/bin/cli.js b/packages/webpack-cli/bin/cli.js
index 1bf0a1be092..34faad08445 100755
--- a/packages/webpack-cli/bin/cli.js
+++ b/packages/webpack-cli/bin/cli.js
@@ -3,7 +3,7 @@
 'use strict';
 require('v8-compile-cache');
 const importLocal = require('import-local');
-const parseArgs = require('../lib/utils/parse-args');
+const parseNodeArgs = require('../lib/utils/parse-node-args');
 const runner = require('../lib/runner');
 
 // Prefer the local installation of webpack-cli
@@ -13,6 +13,6 @@ if (importLocal(__filename)) {
 process.title = 'webpack';
 
 const [, , ...rawArgs] = process.argv;
-const { cliArgs, nodeArgs } = parseArgs(rawArgs);
+const { cliArgs, nodeArgs } = parseNodeArgs(rawArgs);
 
 runner(nodeArgs, cliArgs);
diff --git a/packages/webpack-cli/lib/utils/parse-args.js b/packages/webpack-cli/lib/utils/parse-node-args.js
similarity index 100%
rename from packages/webpack-cli/lib/utils/parse-args.js
rename to packages/webpack-cli/lib/utils/parse-node-args.js
diff --git a/test/node/node.test.js b/test/node/node.test.js
index 1db66c623c3..aa26dd7527e 100644
--- a/test/node/node.test.js
+++ b/test/node/node.test.js
@@ -2,10 +2,10 @@
 const { stat } = require('fs');
 const { resolve } = require('path');
 const { run } = require('../utils/test-utils');
-const parseArgs = require('../../packages/webpack-cli/lib/utils/parse-args');
+const parseNodeArgs = require('../../packages/webpack-cli/lib/utils/parse-node-args');
 
 describe('node flags', () => {
-    it('parseArgs helper must work correctly', () => {
+    it('parseNodeArgs helper must work correctly', () => {
         [
             {
                 rawArgs: ['--foo', '--bar', '--baz=quux'],
@@ -32,7 +32,7 @@ describe('node flags', () => {
                 expectedNodeArgs: ['--name1=value1', '--name2="value2"', '--name3', 'value3', '-k', 'v'],
             },
         ].map(({ rawArgs, expectedNodeArgs, expectedCliArgs }) => {
-            const { nodeArgs, cliArgs } = parseArgs(rawArgs);
+            const { nodeArgs, cliArgs } = parseNodeArgs(rawArgs);
             expect(nodeArgs).toEqual(expectedNodeArgs);
             expect(cliArgs).toEqual(expectedCliArgs);
         });

From 03b76183ad50a3ffbab8b119caedee6e3d8c763e Mon Sep 17 00:00:00 2001
From: Kirill Nagaitsev <knagaitsev1@gmail.com>
Date: Thu, 23 Apr 2020 21:28:11 -0500
Subject: [PATCH 31/43] chore: added arg-parser tests

---
 .../webpack-cli/__tests__/arg-parser.test.js  | 183 ++++++++++++++++++
 packages/webpack-cli/lib/utils/arg-parser.js  |   6 +
 2 files changed, 189 insertions(+)
 create mode 100644 packages/webpack-cli/__tests__/arg-parser.test.js

diff --git a/packages/webpack-cli/__tests__/arg-parser.test.js b/packages/webpack-cli/__tests__/arg-parser.test.js
new file mode 100644
index 00000000000..112dce8fd4e
--- /dev/null
+++ b/packages/webpack-cli/__tests__/arg-parser.test.js
@@ -0,0 +1,183 @@
+const warnMock = jest.fn();
+jest.mock('../lib/utils/logger', () => {
+    return {
+        warn: warnMock,
+    };
+});
+jest.spyOn(process, 'exit').mockImplementation(() => {});
+
+const argParser = require('../lib/utils/arg-parser');
+const { core } = require('../lib/utils/cli-flags');
+
+const basicOptions = [
+    {
+        name: 'bool-flag',
+        alias: 'b',
+        usage: '--bool-flag',
+        type: Boolean,
+        description: 'boolean flag',
+    },
+    {
+        name: 'string-flag',
+        usage: '--string-flag <value>',
+        type: String,
+        description: 'string flag',
+    },
+    {
+        name: 'string-flag-with-default',
+        usage: '--string-flag-with-default <value>',
+        type: String,
+        description: 'string flag',
+        defaultValue: 'default-value',
+    },
+];
+
+const helpAndVersionOptions = basicOptions.slice(0);
+helpAndVersionOptions.push(
+    {
+        name: 'help',
+        usage: '--help',
+        type: Boolean,
+        description: 'help',
+    },
+    {
+        name: 'version',
+        alias: 'v',
+        usage: '--version',
+        type: Boolean,
+        description: 'version',
+    },
+);
+
+describe('arg-parser', () => {
+    beforeEach(() => {
+        warnMock.mockClear();
+    });
+
+    it('parses no flags', () => {
+        const res = argParser(basicOptions, [], true);
+        expect(res.unknownArgs.length).toEqual(0);
+        expect(res.opts).toEqual({
+            stringFlagWithDefault: 'default-value',
+        });
+        expect(warnMock.mock.calls.length).toEqual(0);
+    });
+
+    it('parses basic flags', () => {
+        const res = argParser(basicOptions, ['--bool-flag', '--string-flag', 'val'], true);
+        expect(res.unknownArgs.length).toEqual(0);
+        expect(res.opts).toEqual({
+            boolFlag: true,
+            stringFlag: 'val',
+            stringFlagWithDefault: 'default-value',
+        });
+        expect(warnMock.mock.calls.length).toEqual(0);
+    });
+
+    it('parses negated boolean flags', () => {
+        const res = argParser(basicOptions, ['--no-bool-flag'], true);
+        expect(res.unknownArgs.length).toEqual(0);
+        expect(res.opts).toEqual({
+            boolFlag: false,
+            stringFlagWithDefault: 'default-value',
+        });
+        expect(warnMock.mock.calls.length).toEqual(0);
+    });
+
+    it('parses boolean flag alias', () => {
+        const res = argParser(basicOptions, ['-b'], true);
+        expect(res.unknownArgs.length).toEqual(0);
+        expect(res.opts).toEqual({
+            boolFlag: true,
+            stringFlagWithDefault: 'default-value',
+        });
+        expect(warnMock.mock.calls.length).toEqual(0);
+    });
+
+    it('warns on usage of both flag and same negated flag, setting it to false', () => {
+        const res = argParser(basicOptions, ['--bool-flag', '--no-bool-flag'], true);
+        expect(res.unknownArgs.length).toEqual(0);
+        expect(res.opts).toEqual({
+            boolFlag: false,
+            stringFlagWithDefault: 'default-value',
+        });
+        expect(warnMock.mock.calls.length).toEqual(1);
+        expect(warnMock.mock.calls[0][0]).toContain('You provided both --bool-flag and --no-bool-flag');
+    });
+
+    it('warns on usage of both flag and same negated flag, setting it to true', () => {
+        const res = argParser(basicOptions, ['--no-bool-flag', '--bool-flag'], true);
+        expect(res.unknownArgs.length).toEqual(0);
+        expect(res.opts).toEqual({
+            boolFlag: true,
+            stringFlagWithDefault: 'default-value',
+        });
+        expect(warnMock.mock.calls.length).toEqual(1);
+        expect(warnMock.mock.calls[0][0]).toContain('You provided both --bool-flag and --no-bool-flag');
+    });
+
+    it('warns on usage of both flag alias and same negated flag, setting it to true', () => {
+        const res = argParser(basicOptions, ['--no-bool-flag', '-b'], true);
+        expect(res.unknownArgs.length).toEqual(0);
+        expect(res.opts).toEqual({
+            boolFlag: true,
+            stringFlagWithDefault: 'default-value',
+        });
+        expect(warnMock.mock.calls.length).toEqual(1);
+        expect(warnMock.mock.calls[0][0]).toContain('You provided both -b and --no-bool-flag');
+    });
+
+    it('parses string flag using equals sign', () => {
+        const res = argParser(basicOptions, ['--string-flag=val'], true);
+        expect(res.unknownArgs.length).toEqual(0);
+        expect(res.opts).toEqual({
+            stringFlag: 'val',
+            stringFlagWithDefault: 'default-value',
+        });
+        expect(warnMock.mock.calls.length).toEqual(0);
+    });
+
+    it('handles additional node args from argv', () => {
+        const res = argParser(basicOptions, ['node', 'index.js', '--bool-flag', '--string-flag', 'val'], false);
+        expect(res.unknownArgs.length).toEqual(0);
+        expect(res.opts).toEqual({
+            boolFlag: true,
+            stringFlag: 'val',
+            stringFlagWithDefault: 'default-value',
+        });
+        expect(warnMock.mock.calls.length).toEqual(0);
+    });
+
+    it('handles unknown args', () => {
+        const res = argParser(basicOptions, ['--unknown-arg', '-b', 'no-leading-dashes'], true);
+        expect(res.unknownArgs).toEqual(['--unknown-arg', 'no-leading-dashes']);
+        expect(res.opts).toEqual({
+            boolFlag: true,
+            stringFlagWithDefault: 'default-value',
+        });
+        expect(warnMock.mock.calls.length).toEqual(0);
+    });
+
+    it('calls help callback on --help', () => {
+        const helpCb = jest.fn();
+        argParser(helpAndVersionOptions, ['--help'], true, '', helpCb);
+        expect(helpCb.mock.calls.length).toEqual(1);
+        expect(helpCb.mock.calls[0][0]).toEqual(['--help']);
+    });
+
+    it('calls version callback on --version', () => {
+        const versionCb = jest.fn();
+        argParser(helpAndVersionOptions, ['--version'], true, '', () => {}, versionCb);
+        expect(versionCb.mock.calls.length).toEqual(1);
+    });
+
+    it('parses webpack args', () => {
+        const res = argParser(core, ['--entry', 'test.js', '--hot', '-o', './dist/', '--no-watch'], true);
+        expect(res.unknownArgs.length).toEqual(0);
+        expect(res.opts.entry).toEqual('test.js');
+        expect(res.opts.hot).toBeTruthy();
+        expect(res.opts.output).toEqual('./dist/');
+        expect(res.opts.watch).toBeFalsy();
+        expect(warnMock.mock.calls.length).toEqual(0);
+    });
+});
diff --git a/packages/webpack-cli/lib/utils/arg-parser.js b/packages/webpack-cli/lib/utils/arg-parser.js
index 43bacaa5de1..d0dd153c34f 100644
--- a/packages/webpack-cli/lib/utils/arg-parser.js
+++ b/packages/webpack-cli/lib/utils/arg-parser.js
@@ -81,6 +81,12 @@ function argParser(options, args, argsOnly = false, name = '', helpFunction = un
         }
     });
 
+    Object.keys(opts).forEach((key) => {
+        if (opts[key] === undefined) {
+            delete opts[key];
+        }
+    });
+
     return {
         unknownArgs,
         opts,

From 575fbe80a30bc00ffec5883eb6b05e9a80426128 Mon Sep 17 00:00:00 2001
From: Kirill Nagaitsev <knagaitsev1@gmail.com>
Date: Thu, 23 Apr 2020 22:36:08 -0500
Subject: [PATCH 32/43] chore: use args passed to serve

---
 packages/serve/src/index.ts | 17 ++++-------------
 1 file changed, 4 insertions(+), 13 deletions(-)

diff --git a/packages/serve/src/index.ts b/packages/serve/src/index.ts
index 77ed62ab807..10d0ecfa799 100644
--- a/packages/serve/src/index.ts
+++ b/packages/serve/src/index.ts
@@ -2,7 +2,6 @@ import { devServer } from 'webpack-dev-server/bin/cli-flags';
 import WebpackCLI from 'webpack-cli';
 import logger from 'webpack-cli/lib/utils/logger';
 import startDevServer from './startDevServer';
-import argsToCamelCase from './args-to-camel-case';
 
 /**
  *
@@ -11,28 +10,20 @@ import argsToCamelCase from './args-to-camel-case';
  * @param {String[]} args - args processed from the CLI
  * @returns {Function} invokes the devServer API
  */
-export default function serve(): void {
+export default function serve(...args: string[]): void {
     const cli = new WebpackCLI();
     const core = cli.getCoreFlags();
 
-    const filteredArgs = process.argv.filter((arg) => arg != 'serve');
-    const parsedDevServerArgs = cli.argParser(devServer, filteredArgs);
+    const parsedDevServerArgs = cli.argParser(devServer, args, true);
     const devServerArgs = parsedDevServerArgs.opts;
     const parsedWebpackArgs = cli.argParser(core, parsedDevServerArgs.unknownArgs, true, process.title);
     const webpackArgs = parsedWebpackArgs.opts;
-    const finalArgs = argsToCamelCase(devServerArgs || {});
 
     // pass along the 'hot' argument to the dev server if it exists
     if (webpackArgs && webpackArgs.hot !== undefined) {
-        finalArgs['hot'] = webpackArgs.hot;
+        devServerArgs['hot'] = webpackArgs.hot;
     }
 
-    Object.keys(finalArgs).forEach((arg) => {
-        if (finalArgs[arg] === undefined) {
-            delete finalArgs[arg];
-        }
-    });
-
     if (parsedWebpackArgs.unknownArgs.length > 0) {
         parsedWebpackArgs.unknownArgs
             .filter((e) => e)
@@ -43,6 +34,6 @@ export default function serve(): void {
     }
 
     cli.getCompiler(webpackArgs, core).then((compiler): void => {
-        startDevServer(compiler, finalArgs);
+        startDevServer(compiler, devServerArgs);
     });
 }

From fa0f1457c0b1e34c9a1a279f537eca14d8c3bcea Mon Sep 17 00:00:00 2001
From: Kirill Nagaitsev <knagaitsev1@gmail.com>
Date: Thu, 23 Apr 2020 23:07:21 -0500
Subject: [PATCH 33/43] chore: fix stats flag handling

---
 packages/webpack-cli/lib/utils/arg-parser.js | 13 +++++++++----
 packages/webpack-cli/lib/utils/cli-flags.js  |  1 +
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/packages/webpack-cli/lib/utils/arg-parser.js b/packages/webpack-cli/lib/utils/arg-parser.js
index d0dd153c34f..3a4fdf2ab79 100644
--- a/packages/webpack-cli/lib/utils/arg-parser.js
+++ b/packages/webpack-cli/lib/utils/arg-parser.js
@@ -38,10 +38,15 @@ function argParser(options, args, argsOnly = false, name = '', helpFunction = un
     options.reduce((parserInstance, option) => {
         const flags = option.alias ? `-${option.alias}, --${option.name}` : `--${option.name}`;
         const flagsWithType = option.type !== Boolean ? flags + ' <value>' : flags;
-        parserInstance.option(flagsWithType, option.description, option.defaultValue);
-        if (option.type === Boolean) {
-            const negatedFlag = `--no-${option.name}`;
-            parserInstance.option(negatedFlag, `negates ${option.name}`);
+        if (option.type !== Boolean && option.type !== String) {
+            // in this case the type is a parsing function
+            parserInstance.option(flagsWithType, option.description, option.defaultValue, option.type);
+        } else {
+            parserInstance.option(flagsWithType, option.description, option.defaultValue);
+            if (option.type === Boolean) {
+                const negatedFlag = `--no-${option.name}`;
+                parserInstance.option(negatedFlag, `negates ${option.name}`);
+            }
         }
         return parserInstance;
     }, parser);
diff --git a/packages/webpack-cli/lib/utils/cli-flags.js b/packages/webpack-cli/lib/utils/cli-flags.js
index def246fe544..65142bb363a 100644
--- a/packages/webpack-cli/lib/utils/cli-flags.js
+++ b/packages/webpack-cli/lib/utils/cli-flags.js
@@ -262,6 +262,7 @@ module.exports = {
                 logger.warn('No value recognised for "stats" option');
                 return 'normal';
             },
+            defaultValue: 'normal',
             group: DISPLAY_GROUP,
             description: 'It instructs webpack on how to treat the stats',
             link: 'https://webpack.js.org/configuration/stats/#stats',

From 91ee8f5984185e232cf71829ed42e9deedd4277a Mon Sep 17 00:00:00 2001
From: Kirill Nagaitsev <knagaitsev1@gmail.com>
Date: Thu, 23 Apr 2020 23:35:12 -0500
Subject: [PATCH 34/43] chore: fix function as a custom type

---
 .../webpack-cli/__tests__/arg-parser.test.js   | 18 ++++++++++++++++++
 packages/webpack-cli/lib/utils/arg-parser.js   |  2 +-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/packages/webpack-cli/__tests__/arg-parser.test.js b/packages/webpack-cli/__tests__/arg-parser.test.js
index 112dce8fd4e..ab7600321d0 100644
--- a/packages/webpack-cli/__tests__/arg-parser.test.js
+++ b/packages/webpack-cli/__tests__/arg-parser.test.js
@@ -30,6 +30,14 @@ const basicOptions = [
         description: 'string flag',
         defaultValue: 'default-value',
     },
+    {
+        name: 'custom-type-flag',
+        usage: '--custom-type-flag <value>',
+        type: (val) => {
+            return val.split(',');
+        },
+        description: 'custom type flag',
+    },
 ];
 
 const helpAndVersionOptions = basicOptions.slice(0);
@@ -158,6 +166,16 @@ describe('arg-parser', () => {
         expect(warnMock.mock.calls.length).toEqual(0);
     });
 
+    it('handles custom type args', () => {
+        const res = argParser(basicOptions, ['--custom-type-flag', 'val1,val2,val3'], true);
+        expect(res.unknownArgs.length).toEqual(0);
+        expect(res.opts).toEqual({
+            customTypeFlag: ['val1', 'val2', 'val3'],
+            stringFlagWithDefault: 'default-value',
+        });
+        expect(warnMock.mock.calls.length).toEqual(0);
+    });
+
     it('calls help callback on --help', () => {
         const helpCb = jest.fn();
         argParser(helpAndVersionOptions, ['--help'], true, '', helpCb);
diff --git a/packages/webpack-cli/lib/utils/arg-parser.js b/packages/webpack-cli/lib/utils/arg-parser.js
index 3a4fdf2ab79..973b629f504 100644
--- a/packages/webpack-cli/lib/utils/arg-parser.js
+++ b/packages/webpack-cli/lib/utils/arg-parser.js
@@ -40,7 +40,7 @@ function argParser(options, args, argsOnly = false, name = '', helpFunction = un
         const flagsWithType = option.type !== Boolean ? flags + ' <value>' : flags;
         if (option.type !== Boolean && option.type !== String) {
             // in this case the type is a parsing function
-            parserInstance.option(flagsWithType, option.description, option.defaultValue, option.type);
+            parserInstance.option(flagsWithType, option.description, option.type, option.defaultValue);
         } else {
             parserInstance.option(flagsWithType, option.description, option.defaultValue);
             if (option.type === Boolean) {

From 9240879df178ea970f20ee3d6d0d49cdbb6fadac Mon Sep 17 00:00:00 2001
From: Kirill Nagaitsev <knagaitsev1@gmail.com>
Date: Thu, 23 Apr 2020 23:37:11 -0500
Subject: [PATCH 35/43] chore: change boolean logic in arg parser

---
 packages/webpack-cli/lib/utils/arg-parser.js | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/packages/webpack-cli/lib/utils/arg-parser.js b/packages/webpack-cli/lib/utils/arg-parser.js
index 973b629f504..da6219c0a74 100644
--- a/packages/webpack-cli/lib/utils/arg-parser.js
+++ b/packages/webpack-cli/lib/utils/arg-parser.js
@@ -38,16 +38,17 @@ function argParser(options, args, argsOnly = false, name = '', helpFunction = un
     options.reduce((parserInstance, option) => {
         const flags = option.alias ? `-${option.alias}, --${option.name}` : `--${option.name}`;
         const flagsWithType = option.type !== Boolean ? flags + ' <value>' : flags;
-        if (option.type !== Boolean && option.type !== String) {
-            // in this case the type is a parsing function
-            parserInstance.option(flagsWithType, option.description, option.type, option.defaultValue);
-        } else {
+        if (option.type === Boolean || option.type === String) {
             parserInstance.option(flagsWithType, option.description, option.defaultValue);
             if (option.type === Boolean) {
                 const negatedFlag = `--no-${option.name}`;
                 parserInstance.option(negatedFlag, `negates ${option.name}`);
             }
+        } else {
+            // in this case the type is a parsing function
+            parserInstance.option(flagsWithType, option.description, option.type, option.defaultValue);
         }
+
         return parserInstance;
     }, parser);
 

From f4c94dae43f2bcf290f2424b3377f27fec7cc873 Mon Sep 17 00:00:00 2001
From: Kirill Nagaitsev <knagaitsev1@gmail.com>
Date: Thu, 23 Apr 2020 23:51:16 -0500
Subject: [PATCH 36/43] chore: fixed stats test and removed stats custom type

---
 packages/webpack-cli/lib/utils/cli-flags.js | 11 +----------
 test/stats/stats.test.js                    |  1 +
 2 files changed, 2 insertions(+), 10 deletions(-)

diff --git a/packages/webpack-cli/lib/utils/cli-flags.js b/packages/webpack-cli/lib/utils/cli-flags.js
index 65142bb363a..33d752deb84 100644
--- a/packages/webpack-cli/lib/utils/cli-flags.js
+++ b/packages/webpack-cli/lib/utils/cli-flags.js
@@ -1,6 +1,3 @@
-const logger = require('../utils/logger');
-const StatsGroup = require('../groups/StatsGroup');
-
 const HELP_GROUP = 'help';
 const CONFIG_GROUP = 'config';
 const BASIC_GROUP = 'basic';
@@ -255,13 +252,7 @@ module.exports = {
         {
             name: 'stats',
             usage: '--stats verbose',
-            type: (value) => {
-                if (StatsGroup.validOptions().includes(value)) {
-                    return value;
-                }
-                logger.warn('No value recognised for "stats" option');
-                return 'normal';
-            },
+            type: String,
             defaultValue: 'normal',
             group: DISPLAY_GROUP,
             description: 'It instructs webpack on how to treat the stats',
diff --git a/test/stats/stats.test.js b/test/stats/stats.test.js
index 656a6633825..8fb0145fe82 100644
--- a/test/stats/stats.test.js
+++ b/test/stats/stats.test.js
@@ -48,6 +48,7 @@ describe('stats flag', () => {
     it('should warn when an unknown flag stats value is passed', () => {
         const { stderr, stdout } = run(__dirname, ['--stats', 'foo']);
         expect(stderr).toBeTruthy();
+        console.log(stderr);
         expect(stderr).toContain('invalid value for stats');
         expect(stdout).toBeTruthy();
     });

From 11282eed90f328c20330c00f8c7964d18056acd2 Mon Sep 17 00:00:00 2001
From: Kirill Nagaitsev <knagaitsev1@gmail.com>
Date: Fri, 24 Apr 2020 12:02:09 -0500
Subject: [PATCH 37/43] chore: removed output todo and added tests for warning

---
 .../webpack-cli/lib/groups/OutputGroup.js     | 10 ++--
 .../output-named-bundles.test.js              | 60 +++++++++++++++++--
 2 files changed, 60 insertions(+), 10 deletions(-)

diff --git a/packages/webpack-cli/lib/groups/OutputGroup.js b/packages/webpack-cli/lib/groups/OutputGroup.js
index 97e3ba0d2af..31de0e6dd66 100644
--- a/packages/webpack-cli/lib/groups/OutputGroup.js
+++ b/packages/webpack-cli/lib/groups/OutputGroup.js
@@ -1,5 +1,6 @@
 const path = require('path');
 const GroupHelper = require('../utils/GroupHelper');
+const logger = require('../utils/logger');
 
 class OutputGroup extends GroupHelper {
     constructor(options) {
@@ -27,10 +28,11 @@ class OutputGroup extends GroupHelper {
         const { args } = this;
         if (args) {
             const { output } = args;
-            // TODO: Remove comment before merge
-            // We need to show warning when empty output flag is supplied
-            // which is set to boolean true by commander
-            if (!output || output === true) {
+
+            if (!output) {
+                logger.warn(
+                    "You provided an empty output value. Falling back to the output value of your webpack config file, or './dist/' if none was provided",
+                );
                 return;
             }
             const outputInfo = path.parse(output);
diff --git a/test/output/named-bundles/output-named-bundles.test.js b/test/output/named-bundles/output-named-bundles.test.js
index 82966106b53..738c33e8032 100644
--- a/test/output/named-bundles/output-named-bundles.test.js
+++ b/test/output/named-bundles/output-named-bundles.test.js
@@ -1,11 +1,24 @@
 'use strict';
 const { stat } = require('fs');
-const { resolve } = require('path');
+const { join, resolve } = require('path');
+const rimraf = require('rimraf');
 const { run } = require('../../utils/test-utils');
 
 describe('output flag named bundles', () => {
+    const clean = () => {
+        rimraf.sync(join(__dirname, 'bin'));
+        rimraf.sync(join(__dirname, 'dist'));
+        rimraf.sync(join(__dirname, 'binary'));
+    };
+
+    beforeEach(clean);
+
+    afterAll(clean);
+
     it('should output file given as flag instead of in configuration', (done) => {
-        run(__dirname, ['-c', resolve(__dirname, 'webpack.config.js'), '--output', './binary/a.bundle.js'], false);
+        const { stderr } = run(__dirname, ['-c', resolve(__dirname, 'webpack.config.js'), '--output', './binary/a.bundle.js'], false);
+        expect(stderr).toBeFalsy();
+
         stat(resolve(__dirname, './binary/a.bundle.js'), (err, stats) => {
             expect(err).toBe(null);
             expect(stats.isFile()).toBe(true);
@@ -14,7 +27,12 @@ describe('output flag named bundles', () => {
     });
 
     it('should create multiple bundles with an overriding flag', (done) => {
-        run(__dirname, ['-c', resolve(__dirname, 'webpack.single.config.js'), '--output', './bin/[name].bundle.js'], false);
+        const { stderr } = run(
+            __dirname,
+            ['-c', resolve(__dirname, 'webpack.single.config.js'), '--output', './bin/[name].bundle.js'],
+            false,
+        );
+        expect(stderr).toBeFalsy();
 
         stat(resolve(__dirname, './bin/b.bundle.js'), (err, stats) => {
             expect(err).toBe(null);
@@ -29,8 +47,7 @@ describe('output flag named bundles', () => {
 
     it('should not throw error on same bundle name for multiple entries with defaults', (done) => {
         const { stderr } = run(__dirname, ['-c', resolve(__dirname, 'webpack.defaults.config.js'), '--defaults'], false);
-
-        expect(stderr).toBe('');
+        expect(stderr).toBeFalsy();
 
         stat(resolve(__dirname, './dist/b.main.js'), (err, stats) => {
             expect(err).toBe(null);
@@ -44,7 +61,8 @@ describe('output flag named bundles', () => {
     });
 
     it('should successfully compile multiple entries', (done) => {
-        run(__dirname, ['-c', resolve(__dirname, 'webpack.multiple.config.js')], false);
+        const { stderr } = run(__dirname, ['-c', resolve(__dirname, 'webpack.multiple.config.js')], false);
+        expect(stderr).toBeFalsy();
 
         stat(resolve(__dirname, './bin/b.bundle.js'), (err, stats) => {
             expect(err).toBe(null);
@@ -56,4 +74,34 @@ describe('output flag named bundles', () => {
         });
         done();
     });
+
+    it('should output file in bin directory using default webpack config with warning for empty output value', (done) => {
+        const { stderr } = run(__dirname, ['--output='], false);
+        expect(stderr).toContain(
+            "You provided an empty output value. Falling back to the output value of your webpack config file, or './dist/' if none was provided",
+        );
+
+        stat(resolve(__dirname, './bin/bundle.js'), (err, stats) => {
+            expect(err).toBe(null);
+            expect(stats.isFile()).toBe(true);
+            done();
+        });
+    });
+
+    it('should output file in dist directory using default value with warning for empty output value', (done) => {
+        const { stderr } = run(__dirname, ['-c', resolve(__dirname, 'webpack.defaults.config.js'), '--defaults', '--output='], false);
+        expect(stderr).toContain(
+            "You provided an empty output value. Falling back to the output value of your webpack config file, or './dist/' if none was provided",
+        );
+
+        stat(resolve(__dirname, './dist/b.main.js'), (err, stats) => {
+            expect(err).toBe(null);
+            expect(stats.isFile()).toBe(true);
+        });
+        stat(resolve(__dirname, './dist/c.main.js'), (err, stats) => {
+            expect(err).toBe(null);
+            expect(stats.isFile()).toBe(true);
+        });
+        done();
+    });
 });

From 8339c7be81d7e69475c13594a483588fc936b947 Mon Sep 17 00:00:00 2001
From: Kirill Nagaitsev <knagaitsev1@gmail.com>
Date: Fri, 24 Apr 2020 12:08:24 -0500
Subject: [PATCH 38/43] chore: changed invalid mode message and updated test

---
 packages/webpack-cli/lib/groups/ZeroConfigGroup.js | 2 +-
 test/mode/prod/prod.test.js                        | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/webpack-cli/lib/groups/ZeroConfigGroup.js b/packages/webpack-cli/lib/groups/ZeroConfigGroup.js
index 7259a4e835b..14f1e491d1f 100644
--- a/packages/webpack-cli/lib/groups/ZeroConfigGroup.js
+++ b/packages/webpack-cli/lib/groups/ZeroConfigGroup.js
@@ -37,7 +37,7 @@ class ZeroConfigGroup extends GroupHelper {
 
             if (this.args.mode) {
                 if (this.args.mode !== PRODUCTION && this.args.mode !== DEVELOPMENT && this.args.mode !== NONE) {
-                    logger.warn('You provided an invalid value for "mode" option.');
+                    logger.warn('You provided an invalid value for "mode" option. Using "production" by default');
                     return PRODUCTION;
                 }
                 return this.args.mode;
diff --git a/test/mode/prod/prod.test.js b/test/mode/prod/prod.test.js
index fe5a6cff333..78353586582 100644
--- a/test/mode/prod/prod.test.js
+++ b/test/mode/prod/prod.test.js
@@ -27,7 +27,7 @@ describe('mode flags', () => {
 
     it('should load a production config when --mode=abcd is passed', (done) => {
         const { stderr, stdout } = run(__dirname, ['--mode', 'abcd']);
-        expect(stderr).toContain('invalid value for "mode"');
+        expect(stderr).toContain('invalid value for "mode" option. Using "production" by default');
         expect(stdout).toBeTruthy();
         stat(resolve(__dirname, './bin/main.js'), (err, stats) => {
             expect(err).toBe(null);

From 426c6666980ac867b3f5e6efb28d163ea6565d2f Mon Sep 17 00:00:00 2001
From: Kirill Nagaitsev <knagaitsev1@gmail.com>
Date: Fri, 24 Apr 2020 12:15:45 -0500
Subject: [PATCH 39/43] chore: add comment about commander negation

---
 packages/webpack-cli/lib/utils/arg-parser.js | 1 +
 1 file changed, 1 insertion(+)

diff --git a/packages/webpack-cli/lib/utils/arg-parser.js b/packages/webpack-cli/lib/utils/arg-parser.js
index da6219c0a74..85d6947c116 100644
--- a/packages/webpack-cli/lib/utils/arg-parser.js
+++ b/packages/webpack-cli/lib/utils/arg-parser.js
@@ -41,6 +41,7 @@ function argParser(options, args, argsOnly = false, name = '', helpFunction = un
         if (option.type === Boolean || option.type === String) {
             parserInstance.option(flagsWithType, option.description, option.defaultValue);
             if (option.type === Boolean) {
+                // commander requires explicitly adding the negated version of boolean flags
                 const negatedFlag = `--no-${option.name}`;
                 parserInstance.option(negatedFlag, `negates ${option.name}`);
             }

From 2deb7e3f5532871448e1c1637bafc4a9d044ac5e Mon Sep 17 00:00:00 2001
From: Kirill Nagaitsev <knagaitsev1@gmail.com>
Date: Fri, 24 Apr 2020 12:27:37 -0500
Subject: [PATCH 40/43] chore: made output tests sync

---
 .../output-named-bundles.test.js              | 80 +++++++------------
 1 file changed, 27 insertions(+), 53 deletions(-)

diff --git a/test/output/named-bundles/output-named-bundles.test.js b/test/output/named-bundles/output-named-bundles.test.js
index 738c33e8032..7a53fb80202 100644
--- a/test/output/named-bundles/output-named-bundles.test.js
+++ b/test/output/named-bundles/output-named-bundles.test.js
@@ -1,5 +1,5 @@
 'use strict';
-const { stat } = require('fs');
+const { statSync } = require('fs');
 const { join, resolve } = require('path');
 const rimraf = require('rimraf');
 const { run } = require('../../utils/test-utils');
@@ -15,18 +15,15 @@ describe('output flag named bundles', () => {
 
     afterAll(clean);
 
-    it('should output file given as flag instead of in configuration', (done) => {
+    it('should output file given as flag instead of in configuration', () => {
         const { stderr } = run(__dirname, ['-c', resolve(__dirname, 'webpack.config.js'), '--output', './binary/a.bundle.js'], false);
         expect(stderr).toBeFalsy();
 
-        stat(resolve(__dirname, './binary/a.bundle.js'), (err, stats) => {
-            expect(err).toBe(null);
-            expect(stats.isFile()).toBe(true);
-            done();
-        });
+        const stats = statSync(resolve(__dirname, './binary/a.bundle.js'));
+        expect(stats.isFile()).toBe(true);
     });
 
-    it('should create multiple bundles with an overriding flag', (done) => {
+    it('should create multiple bundles with an overriding flag', () => {
         const { stderr } = run(
             __dirname,
             ['-c', resolve(__dirname, 'webpack.single.config.js'), '--output', './bin/[name].bundle.js'],
@@ -34,74 +31,51 @@ describe('output flag named bundles', () => {
         );
         expect(stderr).toBeFalsy();
 
-        stat(resolve(__dirname, './bin/b.bundle.js'), (err, stats) => {
-            expect(err).toBe(null);
-            expect(stats.isFile()).toBe(true);
-        });
-        stat(resolve(__dirname, './bin/c.bundle.js'), (err, stats) => {
-            expect(err).toBe(null);
-            expect(stats.isFile()).toBe(true);
-        });
-        done();
+        let stats = statSync(resolve(__dirname, './bin/b.bundle.js'));
+        expect(stats.isFile()).toBe(true);
+        stats = statSync(resolve(__dirname, './bin/c.bundle.js'));
+        expect(stats.isFile()).toBe(true);
     });
 
-    it('should not throw error on same bundle name for multiple entries with defaults', (done) => {
+    it('should not throw error on same bundle name for multiple entries with defaults', () => {
         const { stderr } = run(__dirname, ['-c', resolve(__dirname, 'webpack.defaults.config.js'), '--defaults'], false);
         expect(stderr).toBeFalsy();
 
-        stat(resolve(__dirname, './dist/b.main.js'), (err, stats) => {
-            expect(err).toBe(null);
-            expect(stats.isFile()).toBe(true);
-        });
-        stat(resolve(__dirname, './dist/c.main.js'), (err, stats) => {
-            expect(err).toBe(null);
-            expect(stats.isFile()).toBe(true);
-        });
-        done();
+        let stats = statSync(resolve(__dirname, './dist/b.main.js'));
+        expect(stats.isFile()).toBe(true);
+        stats = statSync(resolve(__dirname, './dist/c.main.js'));
+        expect(stats.isFile()).toBe(true);
     });
 
-    it('should successfully compile multiple entries', (done) => {
+    it('should successfully compile multiple entries', () => {
         const { stderr } = run(__dirname, ['-c', resolve(__dirname, 'webpack.multiple.config.js')], false);
         expect(stderr).toBeFalsy();
 
-        stat(resolve(__dirname, './bin/b.bundle.js'), (err, stats) => {
-            expect(err).toBe(null);
-            expect(stats.isFile()).toBe(true);
-        });
-        stat(resolve(__dirname, './bin/c.bundle.js'), (err, stats) => {
-            expect(err).toBe(null);
-            expect(stats.isFile()).toBe(true);
-        });
-        done();
+        let stats = statSync(resolve(__dirname, './bin/b.bundle.js'));
+        expect(stats.isFile()).toBe(true);
+        stats = statSync(resolve(__dirname, './bin/c.bundle.js'));
+        expect(stats.isFile()).toBe(true);
     });
 
-    it('should output file in bin directory using default webpack config with warning for empty output value', (done) => {
+    it('should output file in bin directory using default webpack config with warning for empty output value', () => {
         const { stderr } = run(__dirname, ['--output='], false);
         expect(stderr).toContain(
             "You provided an empty output value. Falling back to the output value of your webpack config file, or './dist/' if none was provided",
         );
 
-        stat(resolve(__dirname, './bin/bundle.js'), (err, stats) => {
-            expect(err).toBe(null);
-            expect(stats.isFile()).toBe(true);
-            done();
-        });
+        const stats = statSync(resolve(__dirname, './bin/bundle.js'));
+        expect(stats.isFile()).toBe(true);
     });
 
-    it('should output file in dist directory using default value with warning for empty output value', (done) => {
+    it('should output file in dist directory using default value with warning for empty output value', () => {
         const { stderr } = run(__dirname, ['-c', resolve(__dirname, 'webpack.defaults.config.js'), '--defaults', '--output='], false);
         expect(stderr).toContain(
             "You provided an empty output value. Falling back to the output value of your webpack config file, or './dist/' if none was provided",
         );
 
-        stat(resolve(__dirname, './dist/b.main.js'), (err, stats) => {
-            expect(err).toBe(null);
-            expect(stats.isFile()).toBe(true);
-        });
-        stat(resolve(__dirname, './dist/c.main.js'), (err, stats) => {
-            expect(err).toBe(null);
-            expect(stats.isFile()).toBe(true);
-        });
-        done();
+        let stats = statSync(resolve(__dirname, './dist/b.main.js'));
+        expect(stats.isFile()).toBe(true);
+        stats = statSync(resolve(__dirname, './dist/c.main.js'));
+        expect(stats.isFile()).toBe(true);
     });
 });

From dfb6f6c89150434829f2109a409707652076c149 Mon Sep 17 00:00:00 2001
From: Kirill Nagaitsev <knagaitsev1@gmail.com>
Date: Fri, 24 Apr 2020 13:47:18 -0500
Subject: [PATCH 41/43] chore: fix spelling in comment

---
 packages/webpack-cli/lib/utils/arg-parser.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/webpack-cli/lib/utils/arg-parser.js b/packages/webpack-cli/lib/utils/arg-parser.js
index 85d6947c116..6bdfc51f502 100644
--- a/packages/webpack-cli/lib/utils/arg-parser.js
+++ b/packages/webpack-cli/lib/utils/arg-parser.js
@@ -23,7 +23,7 @@ function argParser(options, args, argsOnly = false, name = '', helpFunction = un
         });
     }
 
-    // Use customised help output is avaliable
+    // Use customized help output if available
     if (helpFunction) {
         parser.on('option:help', () => {
             helpFunction(args);

From c068011b0cae00b9071e9e201e93df15780c0a48 Mon Sep 17 00:00:00 2001
From: Kirill Nagaitsev <knagaitsev1@gmail.com>
Date: Sat, 25 Apr 2020 02:12:52 -0500
Subject: [PATCH 42/43] chore: remove unnecessary log

---
 test/stats/stats.test.js | 1 -
 1 file changed, 1 deletion(-)

diff --git a/test/stats/stats.test.js b/test/stats/stats.test.js
index 8fb0145fe82..656a6633825 100644
--- a/test/stats/stats.test.js
+++ b/test/stats/stats.test.js
@@ -48,7 +48,6 @@ describe('stats flag', () => {
     it('should warn when an unknown flag stats value is passed', () => {
         const { stderr, stdout } = run(__dirname, ['--stats', 'foo']);
         expect(stderr).toBeTruthy();
-        console.log(stderr);
         expect(stderr).toContain('invalid value for stats');
         expect(stdout).toBeTruthy();
     });

From 9351796400bad7a0f9739a49bb2651396ccbd875 Mon Sep 17 00:00:00 2001
From: Kirill Nagaitsev <knagaitsev1@gmail.com>
Date: Sat, 25 Apr 2020 02:34:01 -0500
Subject: [PATCH 43/43] chore: add runPromptWithAnswers changes for stability

---
 test/init/generator/init-inquirer.test.js |  2 +-
 test/loader/loader.test.js                |  2 +-
 test/utils/test-utils.js                  | 42 ++++++++++++++++++-----
 3 files changed, 36 insertions(+), 10 deletions(-)

diff --git a/test/init/generator/init-inquirer.test.js b/test/init/generator/init-inquirer.test.js
index 0402c8edf72..2c97c9fd71b 100644
--- a/test/init/generator/init-inquirer.test.js
+++ b/test/init/generator/init-inquirer.test.js
@@ -22,7 +22,7 @@ describe('init', () => {
     });
 
     it('should scaffold when given answers', async () => {
-        const stdout = await runPromptWithAnswers(genPath, ['init'], ['N', ENTER, ENTER, ENTER, ENTER, ENTER, ENTER, ENTER]);
+        const { stdout } = await runPromptWithAnswers(genPath, ['init'], ['N', ENTER, ENTER, ENTER, ENTER, ENTER, ENTER, ENTER]);
 
         expect(stdout).toBeTruthy();
         expect(stdout).toContain(firstPrompt);
diff --git a/test/loader/loader.test.js b/test/loader/loader.test.js
index 0aec72825d8..49e625a9a5e 100644
--- a/test/loader/loader.test.js
+++ b/test/loader/loader.test.js
@@ -31,7 +31,7 @@ describe('loader command', () => {
     });
 
     it('should scaffold loader template with a given name', async () => {
-        const stdout = await runPromptWithAnswers(__dirname, ['loader'], [loaderName, ENTER]);
+        const { stdout } = await runPromptWithAnswers(__dirname, ['loader'], [loaderName, ENTER]);
 
         expect(stdout).toContain(firstPrompt);
 
diff --git a/test/utils/test-utils.js b/test/utils/test-utils.js
index 78d049c9693..d107e50de74 100644
--- a/test/utils/test-utils.js
+++ b/test/utils/test-utils.js
@@ -67,17 +67,24 @@ function runWatch({ testCase, args = [], setOutput = true, outputKillStr = 'Time
     });
 }
 
-function runAndGetWatchProc(testCase, args = [], setOutput = true) {
+function runAndGetWatchProc(testCase, args = [], setOutput = true, input = '', forcePipe = false) {
     const cwd = path.resolve(testCase);
 
     const outputPath = path.resolve(testCase, 'bin');
     const argsWithOutput = setOutput ? args.concat('--output', outputPath) : args;
 
-    const webpackProc = execa(WEBPACK_PATH, argsWithOutput, {
+    const options = {
         cwd,
         reject: false,
-        stdio: ENABLE_LOG_COMPILATION ? 'inherit' : 'pipe',
-    });
+        stdio: ENABLE_LOG_COMPILATION && !forcePipe ? 'inherit' : 'pipe',
+    };
+
+    // some tests don't work if the input option is an empty string
+    if (input) {
+        options.input = input;
+    }
+
+    const webpackProc = execa(WEBPACK_PATH, argsWithOutput, options);
 
     return webpackProc;
 }
@@ -86,8 +93,8 @@ function runAndGetWatchProc(testCase, args = [], setOutput = true) {
  * @param {string} location location of current working directory
  * @param {string[]} answers answers to be passed to stdout for inquirer question
  */
-const runPromptWithAnswers = async (location, args, answers) => {
-    const runner = runAndGetWatchProc(location, args, false);
+const runPromptWithAnswers = (location, args, answers) => {
+    const runner = runAndGetWatchProc(location, args, false, '', true);
     runner.stdin.setDefaultEncoding('utf-8');
 
     // Simulate answers by sending the answers after waiting for 2s
@@ -102,14 +109,33 @@ const runPromptWithAnswers = async (location, args, answers) => {
         });
     }, Promise.resolve());
 
-    await simulateAnswers.then(() => {
+    simulateAnswers.then(() => {
         runner.stdin.end();
     });
 
     return new Promise((resolve) => {
+        const obj = {};
+        let stdoutDone = false;
+        let stderrDone = false;
         runner.stdout.pipe(
             concat((result) => {
-                resolve(result.toString());
+                stdoutDone = true;
+                obj.stdout = result.toString();
+                if (stderrDone) {
+                    runner.kill('SIGKILL');
+                    resolve(obj);
+                }
+            }),
+        );
+
+        runner.stderr.pipe(
+            concat((result) => {
+                stderrDone = true;
+                obj.stderr = result.toString();
+                if (stdoutDone) {
+                    runner.kill('SIGKILL');
+                    resolve(obj);
+                }
             }),
         );
     });