test: add some es-modules concatenation cases (#566)

.editorconfig

@@ -11,3 +11,6 @@ trim_trailing_whitespace = true
 [*.md]
 insert_final_newline = true
 trim_trailing_whitespace = false
+
+[test/cases/**]
+insert_final_newline = false

test/cases/es-module-concatenation/a.css

@@ -0,0 +1,3 @@
+.a {
+  background: red;
+}

test/cases/es-module-concatenation/b.css

@@ -0,0 +1,3 @@
+.b {
+  background: green;
+}

test/cases/es-module-concatenation/c.css

@@ -0,0 +1,3 @@
+.c {
+  background: blue;
+}

test/cases/es-module-concatenation/expected/webpack-4/main.css

@@ -0,0 +1,12 @@
+.a {
+  background: red;
+}
+
+.b {
+  background: green;
+}
+
+.c {
+  background: blue;
+}
+

test/cases/es-module-concatenation/expected/webpack-4/main.js

@@ -0,0 +1,111 @@
+/******/ (function(modules) { // webpackBootstrap
+/******/ 	// The module cache
+/******/ 	var installedModules = {};
+/******/
+/******/ 	// The require function
+/******/ 	function __webpack_require__(moduleId) {
+/******/
+/******/ 		// Check if module is in cache
+/******/ 		if(installedModules[moduleId]) {
+/******/ 			return installedModules[moduleId].exports;
+/******/ 		}
+/******/ 		// Create a new module (and put it into the cache)
+/******/ 		var module = installedModules[moduleId] = {
+/******/ 			i: moduleId,
+/******/ 			l: false,
+/******/ 			exports: {}
+/******/ 		};
+/******/
+/******/ 		// Execute the module function
+/******/ 		modules[moduleId].call(module.exports, module, module.exports, __webpack_require__);
+/******/
+/******/ 		// Flag the module as loaded
+/******/ 		module.l = true;
+/******/
+/******/ 		// Return the exports of the module
+/******/ 		return module.exports;
+/******/ 	}
+/******/
+/******/
+/******/ 	// expose the modules object (__webpack_modules__)
+/******/ 	__webpack_require__.m = modules;
+/******/
+/******/ 	// expose the module cache
+/******/ 	__webpack_require__.c = installedModules;
+/******/
+/******/ 	// define getter function for harmony exports
+/******/ 	__webpack_require__.d = function(exports, name, getter) {
+/******/ 		if(!__webpack_require__.o(exports, name)) {
+/******/ 			Object.defineProperty(exports, name, { enumerable: true, get: getter });
+/******/ 		}
+/******/ 	};
+/******/
+/******/ 	// define __esModule on exports
+/******/ 	__webpack_require__.r = function(exports) {
+/******/ 		if(typeof Symbol !== 'undefined' && Symbol.toStringTag) {
+/******/ 			Object.defineProperty(exports, Symbol.toStringTag, { value: 'Module' });
+/******/ 		}
+/******/ 		Object.defineProperty(exports, '__esModule', { value: true });
+/******/ 	};
+/******/
+/******/ 	// create a fake namespace object
+/******/ 	// mode & 1: value is a module id, require it
+/******/ 	// mode & 2: merge all properties of value into the ns
+/******/ 	// mode & 4: return value when already ns object
+/******/ 	// mode & 8|1: behave like require
+/******/ 	__webpack_require__.t = function(value, mode) {
+/******/ 		if(mode & 1) value = __webpack_require__(value);
+/******/ 		if(mode & 8) return value;
+/******/ 		if((mode & 4) && typeof value === 'object' && value && value.__esModule) return value;
+/******/ 		var ns = Object.create(null);
+/******/ 		__webpack_require__.r(ns);
+/******/ 		Object.defineProperty(ns, 'default', { enumerable: true, value: value });
+/******/ 		if(mode & 2 && typeof value != 'string') for(var key in value) __webpack_require__.d(ns, key, function(key) { return value[key]; }.bind(null, key));
+/******/ 		return ns;
+/******/ 	};
+/******/
+/******/ 	// getDefaultExport function for compatibility with non-harmony modules
+/******/ 	__webpack_require__.n = function(module) {
+/******/ 		var getter = module && module.__esModule ?
+/******/ 			function getDefault() { return module['default']; } :
+/******/ 			function getModuleExports() { return module; };
+/******/ 		__webpack_require__.d(getter, 'a', getter);
+/******/ 		return getter;
+/******/ 	};
+/******/
+/******/ 	// Object.prototype.hasOwnProperty.call
+/******/ 	__webpack_require__.o = function(object, property) { return Object.prototype.hasOwnProperty.call(object, property); };
+/******/
+/******/ 	// __webpack_public_path__
+/******/ 	__webpack_require__.p = "";
+/******/
+/******/
+/******/ 	// Load entry module and return exports
+/******/ 	return __webpack_require__(__webpack_require__.s = 0);
+/******/ })
+/************************************************************************/
+/******/ ([
+/* 0 */
+/***/ (function(module, __webpack_exports__, __webpack_require__) {
+
+"use strict";
+// ESM COMPAT FLAG
+__webpack_require__.r(__webpack_exports__);
+
+// CONCATENATED MODULE: ./a.css
+// extracted by mini-css-extract-plugin
+
+// CONCATENATED MODULE: ./b.css
+// extracted by mini-css-extract-plugin
+
+// CONCATENATED MODULE: ./c.css
+// extracted by mini-css-extract-plugin
+
+// CONCATENATED MODULE: ./index.js
+
+
+
+
+
+/***/ })
+/******/ ]);

test/cases/es-module-concatenation/expected/webpack-5/main.css

@@ -0,0 +1,12 @@
+.a {
+  background: red;
+}
+
+.b {
+  background: green;
+}
+
+.c {
+  background: blue;
+}
+

test/cases/es-module-concatenation/expected/webpack-5/main.js

@@ -0,0 +1,69 @@
+/******/ (() => { // webpackBootstrap
+/******/ 	"use strict";
+/******/ 	var __webpack_modules__ = ([
+/* 0 */
+/***/ ((__unused_webpack_module, __webpack_exports__, __webpack_require__) => {
+
+// ESM COMPAT FLAG
+__webpack_require__.r(__webpack_exports__);
+
+// CONCATENATED MODULE: ./a.css
+// extracted by mini-css-extract-plugin
+
+// CONCATENATED MODULE: ./b.css
+// extracted by mini-css-extract-plugin
+
+// CONCATENATED MODULE: ./c.css
+// extracted by mini-css-extract-plugin
+
+// CONCATENATED MODULE: ./index.js
+
+
+
+
+
+/***/ })
+/******/ 	]);
+/************************************************************************/
+/******/ 	// The module cache
+/******/ 	var __webpack_module_cache__ = {};
+/******/ 	
+/******/ 	// The require function
+/******/ 	function __webpack_require__(moduleId) {
+/******/ 		// Check if module is in cache
+/******/ 		if(__webpack_module_cache__[moduleId]) {
+/******/ 			return __webpack_module_cache__[moduleId].exports;
+/******/ 		}
+/******/ 		// Create a new module (and put it into the cache)
+/******/ 		var module = __webpack_module_cache__[moduleId] = {
+/******/ 			// no module.id needed
+/******/ 			// no module.loaded needed
+/******/ 			exports: {}
+/******/ 		};
+/******/ 	
+/******/ 		// Execute the module function
+/******/ 		__webpack_modules__[moduleId](module, module.exports, __webpack_require__);
+/******/ 	
+/******/ 		// Return the exports of the module
+/******/ 		return module.exports;
+/******/ 	}
+/******/ 	
+/************************************************************************/
+/******/ 	/* webpack/runtime/make namespace object */
+/******/ 	(() => {
+/******/ 		// define __esModule on exports
+/******/ 		__webpack_require__.r = (exports) => {
+/******/ 			if(typeof Symbol !== 'undefined' && Symbol.toStringTag) {
+/******/ 				Object.defineProperty(exports, Symbol.toStringTag, { value: 'Module' });
+/******/ 			}
+/******/ 			Object.defineProperty(exports, '__esModule', { value: true });
+/******/ 		};
+/******/ 	})();
+/******/ 	
+/************************************************************************/
+/******/ 	// startup
+/******/ 	// Load entry module
+/******/ 	__webpack_require__(0);
+/******/ 	// This entry module used 'exports' so it can't be inlined
+/******/ })()
+;

test/cases/es-module-concatenation/index.js

@@ -0,0 +1,3 @@
+import './a.css';
+import './b.css';
+import './c.css';

test/cases/es-module-concatenation/webpack.config.js

@@ -0,0 +1,29 @@
+import Self from '../../../src';
+
+module.exports = {
+  entry: './index.js',
+  optimization: {
+    concatenateModules: true,
+  },
+  module: {
+    rules: [
+      {
+        test: /\.css$/,
+        use: [
+          {
+            loader: Self.loader,
+            options: {
+              esModule: true,
+            },
+          },
+          'css-loader',
+        ],
+      },
+    ],
+  },
+  plugins: [
+    new Self({
+      filename: '[name].css',
+    }),
+  ],
+};

test/enforce-esm.test.js

@@ -1,5 +1,9 @@
+import webpack from 'webpack';
+
 import { getCompiler, source, compile } from './helpers';
 
+const isWebpack5 = webpack.version[0] === '5';
+
 it('should enforce esm for empty module with options.esModule', async (done) => {
   const compiler = getCompiler(
     './esm.js',
@@ -11,6 +15,7 @@ it('should enforce esm for empty module with options.esModule', async (done) =>
   );
   const stats = await compile(compiler);
   expect(stats.hasErrors()).toBe(false);
+  expect(stats.compilation.modules.length).toBe(isWebpack5 ? 4 : 2);
   expect(source('./simple.css', stats)).toMatchInlineSnapshot(`
     "// extracted by mini-css-extract-plugin
     export {};"
@@ -29,6 +34,7 @@ it('should keep empty module without options.esModule', async (done) => {
   );
   const stats = await compile(compiler);
   expect(stats.hasErrors()).toBe(false);
+  expect(stats.compilation.modules.length).toBe(isWebpack5 ? 7 : 3);
   expect(source('./simple.css', stats)).toMatchInlineSnapshot(
     `"// extracted by mini-css-extract-plugin"`
   );