feat(multi-entry): add preserveModules option

packages/multi-entry/README.md

@@ -80,6 +80,13 @@ Default: `'multi-entry.js'`
 
 `entryFileName` changes the name of the generated entry file. By default, it will override `outputOptions.entryFileNames` to be `'multi-entry.js'`.
 
+### `preserveModules`
+
+Type: `Boolean`<br>
+Default: `false`
+
+`preserveModules` is to be used in conjunction with [`output.preserveModules`](https://rollupjs.org/guide/en/#outputpreservemodules). If `true`, overrides the `entryFileName` option to be output.entryFileNames. If `false`, the plugin will respect the `entryFileName` option.
+
 ## Supported Input Types
 
 This plugin extends Rollup's `input` option to support multiple new value types, in addition to a `String` specifying a path to a file.

packages/multi-entry/src/index.js

@@ -53,7 +53,7 @@ export default function multiEntry(conf = {}) {
     outputOptions(options) {
       return {
         ...options,
-        entryFileNames: config.entryFileName
+        entryFileNames: config.preserveModules ? options.entryFileNames : config.entryFileName
       };
     },
 

packages/multi-entry/test/test.mjs

@@ -91,3 +91,43 @@ test('works as CJS plugin', async (t) => {
   const code = await getCode(bundle);
   t.truthy(code.includes('exports.zero = zero;'));
 });
+
+test('maintains filename when preserveModules = true', async (t) => {
+  const bundle = await rollup({
+    input: 'test/fixtures/{0,1}.js',
+    plugins: [multiEntry({ preserveModules: true, entryFileName: 'testing.js' })]
+  });
+
+  const files = await getCode(bundle, { format: 'cjs', preserveModules: true }, true);
+
+  const nonVirtualFiles = files.filter(({ fileName }) => !fileName.includes('_virtual/'));
+
+  t.is(nonVirtualFiles.length, 2);
+
+  t.truthy(nonVirtualFiles.find(({ fileName }) => fileName === '0.js'));
+  t.truthy(nonVirtualFiles.find(({ fileName }) => fileName === '1.js'));
+});
+
+test('makes a bundle with entryFileName as the output.entryFileName when preserveModules = true and entryName is not set', async (t) => {
+  const bundle = await rollup({
+    input: 'test/fixtures/{0,1}.js',
+    plugins: [multiEntry({ preserveModules: true })]
+  });
+
+  const files = await getCode(
+    bundle,
+    {
+      format: 'cjs',
+      preserveModules: true,
+      entryFileNames: (c) => `entry-${c.name}.js`
+    },
+    true
+  );
+
+  const nonVirtualFiles = files.filter(({ fileName }) => !fileName.includes('_virtual/'));
+
+  t.is(nonVirtualFiles.length, 2);
+
+  t.truthy(nonVirtualFiles.find(({ fileName }) => fileName === 'entry-0.js'));
+  t.truthy(nonVirtualFiles.find(({ fileName }) => fileName === 'entry-1.js'));
+});

packages/multi-entry/types/index.d.ts

@@ -26,6 +26,13 @@ interface RollupMultiEntryOptions {
    * @default 'multi-entry.js'
    */
   entryFileName?: string;
+  /**
+   * The preserveModules option is to be used in conjunction with output.preserveModules ({@link https://rollupjs.org/guide/en/#outputpreservemodules}).
+   * If `true`, overrides the `entryFileName` option to be output.entryFileNames.
+   * If `false`, the plugin will respect the `entryFileName` option.
+   * @default false
+   */
+  preserveModules?: boolean;
 }
 
 /**