Add new test for virtual file output when modifying entryFileNames

Use entryFileNames to change the extension of the filename to be mjs,
and see that the file created from the virtual file chunk has a .mjs
extension

Note that the amd definition contains the .mjs extension, as amd ids only
strip the .js file extension, which is slightly odd but probably ok as
this amd is not the targetted usecase for this behaviour

test/chunking-form/samples/preserve-modules-virtual-modules-follows-entry-filenames/_config.js

@@ -0,0 +1,23 @@
+module.exports = {
+	description:
+		'Generates actual files whose filename adheres to entryFileNames for virtual modules when preserving modules',
+	options: {
+		input: 'main.js',
+		output: { preserveModules: true, entryFileNames: '[name][assetExtname].mjs' },
+		plugins: [
+			{
+				resolveId(id) {
+					if (id === '\0virtualModule') return id;
+				},
+				load(id) {
+					if (id !== '\0virtualModule') return null;
+					return 'export const virtual = "Virtual!";\n';
+				},
+				transform(code, id) {
+					if (id === '\0virtualModule') return null;
+					return 'import {virtual} from "\0virtualModule";\n' + code;
+				}
+			}
+		]
+	}
+};

test/chunking-form/samples/preserve-modules-virtual-modules-follows-entry-filenames/_expected/amd/_virtual/_virtualModule.mjs

@@ -0,0 +1,9 @@
+define(['exports'], (function (exports) { 'use strict';
+
+	const virtual = "Virtual!";
+
+	exports.virtual = virtual;
+
+	Object.defineProperty(exports, '__esModule', { value: true });
+
+}));

test/chunking-form/samples/preserve-modules-virtual-modules-follows-entry-filenames/_expected/amd/main.mjs

@@ -0,0 +1,5 @@
+define(['./_virtual/_virtualModule.mjs'], (function (_virtualModule) { 'use strict';
+
+	assert.equal(_virtualModule.virtual, 'Virtual!');
+
+}));

test/chunking-form/samples/preserve-modules-virtual-modules-follows-entry-filenames/_expected/cjs/_virtual/_virtualModule.mjs

@@ -0,0 +1,7 @@
+'use strict';
+
+Object.defineProperty(exports, '__esModule', { value: true });
+
+const virtual = "Virtual!";
+
+exports.virtual = virtual;

test/chunking-form/samples/preserve-modules-virtual-modules-follows-entry-filenames/_expected/cjs/main.mjs

@@ -0,0 +1,5 @@
+'use strict';
+
+var _virtualModule = require('./_virtual/_virtualModule.mjs');
+
+assert.equal(_virtualModule.virtual, 'Virtual!');

test/chunking-form/samples/preserve-modules-virtual-modules-follows-entry-filenames/_expected/es/_virtual/_virtualModule.mjs

@@ -0,0 +1,3 @@
+const virtual = "Virtual!";
+
+export { virtual };

test/chunking-form/samples/preserve-modules-virtual-modules-follows-entry-filenames/_expected/es/main.mjs

@@ -0,0 +1,3 @@
+import { virtual } from './_virtual/_virtualModule.mjs';
+
+assert.equal(virtual, 'Virtual!');

test/chunking-form/samples/preserve-modules-virtual-modules-follows-entry-filenames/_expected/system/_virtual/_virtualModule.mjs

@@ -0,0 +1,10 @@
+System.register([], (function (exports) {
+	'use strict';
+	return {
+		execute: (function () {
+
+			const virtual = exports('virtual', "Virtual!");
+
+		})
+	};
+}));

test/chunking-form/samples/preserve-modules-virtual-modules-follows-entry-filenames/_expected/system/main.mjs

@@ -0,0 +1,14 @@
+System.register(['./_virtual/_virtualModule.mjs'], (function () {
+	'use strict';
+	var virtual;
+	return {
+		setters: [function (module) {
+			virtual = module.virtual;
+		}],
+		execute: (function () {
+
+			assert.equal(virtual, 'Virtual!');
+
+		})
+	};
+}));

test/chunking-form/samples/preserve-modules-virtual-modules-follows-entry-filenames/main.js

@@ -0,0 +1 @@
+assert.equal(virtual, 'Virtual!');