test: improve tests for --merge (#2399)

test/merge/config/1.js

@@ -1,6 +1,10 @@
+const WebpackCLITestPlugin = require('../../utils/webpack-cli-test-plugin');
+
 module.exports = {
-    entry: './old_entry.js',
+    entry: './first-entry.js',
+    mode: 'development',
     output: {
-        filename: 'badfile.js',
+        filename: 'first-output.js',
     },
+    plugins: [new WebpackCLITestPlugin()],
 };

test/merge/config/2.js

@@ -1,6 +1,7 @@
 module.exports = {
-    entry: './some_entry.js',
+    entry: './second-entry.js',
+    target: 'node',
     output: {
-        filename: 'merged.js',
+        filename: 'second-output.js',
     },
 };

test/merge/config/3.js

@@ -0,0 +1,6 @@
+module.exports = {
+    entry: './third-entry.js',
+    output: {
+        filename: 'third-output.js',
+    },
+};

test/merge/config/first-entry.js

@@ -0,0 +1 @@
+console.log('first');

test/merge/config/merge-config.test.js

@@ -8,19 +8,35 @@ describe('merge flag configuration', () => {
 
         expect(exitCode).toBe(0);
         expect(stderr).toBeFalsy();
-        expect(stdout).toContain('option has not been set, webpack will fallback to');
+        expect(stdout).toContain('WebpackCLITestPlugin'); // from 1.js
+        expect(stdout).toContain('second-output.js'); // from 2.js
+    });
+
+    it('merges more than two configurations together', () => {
+        const { exitCode, stderr, stdout } = run(
+            __dirname,
+            ['--config', './1.js', '--config', './2.js', '--config', './3.js', '--merge'],
+            false,
+        );
+
+        expect(exitCode).toBe(0);
+        expect(stderr).toBeFalsy();
+        expect(stdout).toContain('WebpackCLITestPlugin'); // from 1.js
+        expect(stdout).toContain("target: 'node'"); // from 2.js
+        expect(stdout).toContain('third-output.js'); // from 3.js
     });
 
     it('merges two configurations together with flag alias', () => {
         const { exitCode, stderr, stdout } = run(__dirname, ['--config', './1.js', '--config', './2.js', '-m'], false);
 
         expect(exitCode).toBe(0);
         expect(stderr).toBeFalsy();
-        expect(stdout).toContain('merged.js');
+        expect(stdout).toContain('WebpackCLITestPlugin'); // from 1.js
+        expect(stdout).toContain('second-output.js'); // from 2.js
     });
 
     it('fails when there are less than 2 configurations to merge', () => {
-        const { exitCode, stderr, stdout } = run(__dirname, ['--config', './1.js', '-m'], false);
+        const { exitCode, stderr, stdout } = run(__dirname, ['--config', './1.js', '--merge'], false);
 
         expect(exitCode).toBe(2);
         expect(stderr).toContain('At least two configurations are required for merge.');

test/merge/config/second-entry.js

@@ -0,0 +1 @@
+console.log('second');

test/merge/config/third-entry.js

@@ -0,0 +1 @@
+console.log('third');