Adds a test

__tests__/integration.js

@@ -4,6 +4,8 @@
 import execa from 'execa';
 import makeTemp from './_temp.js';
 import * as fs from '../src/util/fs.js';
+import * as misc from '../src/util/misc.js';
+import * as constants from '../src/constants.js';
 
 jasmine.DEFAULT_TIMEOUT_INTERVAL = 90000;
 
@@ -76,12 +78,37 @@ test('cache folder fallback', async () => {
   const cacheFolder = path.join(cwd, '.cache');
 
   await fs.mkdirp(cacheFolder);
-  await fs.chmod(cacheFolder, 0o000);
 
   const command = path.resolve(__dirname, '../bin/yarn');
   const args = ['--preferred-cache-folder', cacheFolder];
 
   const options = {cwd};
 
-  await Promise.all([execa(command, ['cache', 'dir'].concat(args), options)]);
+  {
+    const {stderr, stdout} = execa(command, ['cache', 'dir'].concat(args), options);
+
+    const stdoutPromise = misc.consumeStream(stdout);
+    const stderrPromise = misc.consumeStream(stderr);
+
+    const [stdoutOutput, stderrOutput] = await Promise.all([stdoutPromise, stderrPromise]);
+
+    expect(stdoutOutput.toString().trim()).toEqual(path.join(cacheFolder, `v${constants.CACHE_VERSION}`));
+    expect(stderrOutput.toString()).not.toMatch(/Skipping preferred cache folder/);
+  }
+
+  await fs.chmod(cacheFolder, 0o000);
+
+  {
+    const {stderr, stdout} = execa(command, ['cache', 'dir'].concat(args), options);
+
+    const stdoutPromise = misc.consumeStream(stdout);
+    const stderrPromise = misc.consumeStream(stderr);
+
+    const [stdoutOutput, stderrOutput] = await Promise.all([stdoutPromise, stderrPromise]);
+
+    expect(stdoutOutput.toString().trim()).toEqual(
+      path.join(constants.PREFERRED_MODULE_CACHE_DIRECTORIES[0], `v${constants.CACHE_VERSION}`),
+    );
+    expect(stderrOutput.toString()).toMatch(/Skipping preferred cache folder/);
+  }
 });

src/cli/commands/cache.js

@@ -55,7 +55,7 @@ export const {run, setFlags, examples} = buildSubCommands('cache', {
   },
 
   dir(config: Config, reporter: Reporter) {
-    reporter.log(config.cacheFolder);
+    reporter.log(config.cacheFolder, {force: true});
   },
 
   async clean(config: Config, reporter: Reporter, flags: Object, args: Array<string>): Promise<void> {

src/cli/index.js

@@ -61,7 +61,7 @@ export function main({
     'rather than installing modules into the node_modules folder relative to the cwd, output them here',
   );
   commander.option('--preferred-cache-folder <path>', 'specify a custom folder to store the yarn cache if possible');
-  commander.option('--cache-folder <path>', 'specify a custom folder to store the yarn cache');
+  commander.option('--cache-folder <path>', 'specify a custom folder that must be used to store the yarn cache');
   commander.option('--mutex <type>[:specifier]', 'use a mutex to ensure only one yarn instance is executing');
   commander.option('--emoji [bool]', 'enable emoji in output', process.platform === 'darwin');
   commander.option('-s, --silent', 'skip Yarn console logs, other types of logs (script output) will be printed');

src/config.js

@@ -288,7 +288,7 @@ export default class Config {
       }
 
       for (let t = 0; t < preferredCacheFolders.length && !cacheRootFolder; ++t) {
-        const tentativeCacheFolder = preferredCacheFolders[t];
+        const tentativeCacheFolder = String(preferredCacheFolders[t]);
 
         try {
           await fs.mkdirp(tentativeCacheFolder);

src/reporters/base-reporter.js

@@ -195,7 +195,7 @@ export default class BaseReporter {
   success(message: string) {}
 
   // a simple log message
-  log(message: string) {}
+  log(message: string, {force = false}: {force?: boolean} = {}) {}
 
   // a shell command has been executed
   command(command: string) {}

src/reporters/console/console-reporter.js

@@ -160,13 +160,13 @@ export default class ConsoleReporter extends BaseReporter {
     this.log(this._prependEmoji(msg, '✨'));
   }
 
-  log(msg: string) {
+  log(msg: string, {force = false}: {force?: boolean} = {}) {
     this._lastCategorySize = 0;
-    this._log(msg);
+    this._log(msg, {force});
   }
 
-  _log(msg: string) {
-    if (this.isSilent) {
+  _log(msg: string, {force = false}: {force?: boolean} = {}) {
+    if (this.isSilent && !force) {
       return;
     }
     clearLine(this.stdout);

src/reporters/lang/en.js

@@ -183,7 +183,7 @@ const messages = {
 
   cacheFolderSkipped: 'Skipping preferred cache folder $0 because it is not writable.',
   cacheFolderMissing:
-    "Yarn hasn't been able to find a cache folder. Please use an explicit --cache-folder option to tell it what location to use, or make one of the preferred locations writable.",
+    "Yarn hasn't been able to find a cache folder it can use. Please use the explicit --cache-folder option to tell it what location to use, or make one of the preferred locations writable.",
   cacheFolderSelected: 'Selected the next writable cache folder in the list, will be $0.',
 
   execMissingCommand: 'Missing command name.',

src/util/misc.js

@@ -2,6 +2,24 @@
 
 const _camelCase = require('camelcase');
 
+export function consumeStream(stream: Object): Promise<Buffer> {
+  return new Promise((resolve, reject) => {
+    const buffers = [];
+
+    stream.on(`data`, buffer => {
+      buffers.push(buffer);
+    });
+
+    stream.on(`end`, () => {
+      resolve(Buffer.concat(buffers));
+    });
+
+    stream.on(`error`, error => {
+      reject(error);
+    });
+  });
+}
+
 export function sortAlpha(a: string, b: string): number {
   // sort alphabetically in a deterministic way
   const shortLen = Math.min(a.length, b.length);