Pass globalPrefix through to serializer and expose to getRunModuleStatement (#1566)

Summary:
Pull Request resolved: #1566

To allow prefixing the global function `__r` (e.g., #1512), expose the prefix to the configured [`getRunModuleStatement`](https://metrobundler.dev/docs/configuration/#getrunmodulestatement), which returns the `__r()` call as a string.

```
 - **[Feature]** Expose `globalPrefix` to `getRunModuleStatement`
```

## Alternative? Runtime prefixing
We could alternatively add prefix at runtime by emitting:
```
"globalThis[__METRO_GLOBAL_PREFIX__ + '__r'](/*...*/)"
```
There are a couple of downsides -
 - These runModule statements are currently outside IIFEs that inject `global` based on (something like) `global = globalThis ?? global ?? window` - we don't rely on the existence of `globalThis` elsewhere (though it's probably safe to now - that's a separate breaking change).
 - Concatenation/interpolation + object access is more verbose and slightly slower, and there's just no need for it in code emitted by Metro itself (as opposed to framework/userland code, which must use it).

Reviewed By: huntie

Differential Revision: D81476621

fbshipit-source-id: 90641cf21491711c56606131ec4c5797b7b00020

Author: robhogan

docs/Configuration.md

@@ -562,7 +562,7 @@ This option only has an effect under the default [`transformerPath`](#transforme
 
 #### `getRunModuleStatement`
 
-Type: `(number | string) => string`
+Type: `(moduleId: number | string, globalPrefix: string) => string`
 
 Specify the format of the initial require statements that are appended at the end of the bundle. By default is `__r(${moduleId});`.
 

packages/metro-config/src/defaults/index.js

@@ -58,7 +58,7 @@ const getDefaultValues = (projectRoot: ?string): ConfigT => ({
 
   serializer: {
     polyfillModuleNames: [],
-    getRunModuleStatement: (moduleId: number | string) =>
+    getRunModuleStatement: (moduleId: number | string, globalPrefix: string) =>
       `__r(${JSON.stringify(moduleId)});`,
     getPolyfills: () => [],
     getModulesRunBeforeMainModule: () => [],

packages/metro-config/src/types.js

@@ -134,7 +134,10 @@ type SerializerConfigT = {
   ) => mixed,
   getModulesRunBeforeMainModule: (entryFilePath: string) => Array<string>,
   getPolyfills: ({platform: ?string, ...}) => $ReadOnlyArray<string>,
-  getRunModuleStatement: (number | string) => string,
+  getRunModuleStatement: (
+    moduleId: number | string,
+    globalPrefix: string,
+  ) => string,
   polyfillModuleNames: $ReadOnlyArray<string>,
   processModuleFilter: (modules: Module<>) => boolean,
   isThirdPartyModule: (module: $ReadOnly<{path: string, ...}>) => boolean,

packages/metro-config/types/types.d.ts

@@ -132,7 +132,10 @@ export interface SerializerConfigT {
   ) => unknown;
   getModulesRunBeforeMainModule: (entryFilePath: string) => string[];
   getPolyfills: (options: {platform: string | null}) => ReadonlyArray<string>;
-  getRunModuleStatement: (moduleId: number | string) => string;
+  getRunModuleStatement: (
+    moduleId: number | string,
+    globalPrefix: string,
+  ) => string;
   polyfillModuleNames: ReadonlyArray<string>;
   processModuleFilter: (modules: Module) => boolean;
   isThirdPartyModule: (module: {readonly path: string}) => boolean;

packages/metro/src/DeltaBundler/Serializers/__tests__/baseJSBundle-test.js

@@ -94,8 +94,10 @@ const nonAsciiModule: Module<> = {
   getSource: () => Buffer.from('bar-source'),
 };
 
-const getRunModuleStatement = (moduleId: number | string) =>
-  `require(${JSON.stringify(moduleId)});`;
+const getRunModuleStatement = jest.fn(
+  (moduleId: number | string, globalPrefix: string) =>
+    `require(${JSON.stringify(moduleId)});`,
+);
 
 const transformOptions: TransformInputOptions = {
   customTransformOptions: {},
@@ -107,6 +109,10 @@ const transformOptions: TransformInputOptions = {
   unstable_transformProfile: 'default',
 };
 
+beforeEach(() => {
+  jest.clearAllMocks();
+});
+
 test('should generate a very simple bundle', () => {
   expect(
     baseJSBundle(
@@ -126,6 +132,7 @@ test('should generate a very simple bundle', () => {
         createModuleId: filePath => path.basename(filePath),
         dev: true,
         getRunModuleStatement,
+        globalPrefix: 'customPrefix',
         includeAsyncPaths: false,
         inlineSourceMap: false,
         modulesOnly: false,
@@ -157,6 +164,8 @@ test('should generate a very simple bundle', () => {
       "pre": "__d(function() {/* code for polyfill */});",
     }
   `);
+
+  expect(getRunModuleStatement).toHaveBeenCalledWith('foo', 'customPrefix');
 });
 
 test('should generate a bundle with correct non ascii characters parsing', () => {
@@ -177,6 +186,7 @@ test('should generate a bundle with correct non ascii characters parsing', () =>
         createModuleId: filePath => path.basename(filePath),
         dev: true,
         getRunModuleStatement,
+        globalPrefix: '',
         includeAsyncPaths: false,
         inlineSourceMap: false,
         modulesOnly: false,
@@ -235,6 +245,7 @@ test('should add runBeforeMainModule statements if found in the graph', () => {
         createModuleId: filePath => path.basename(filePath),
         dev: true,
         getRunModuleStatement,
+        globalPrefix: '',
         includeAsyncPaths: false,
         inlineSourceMap: false,
         modulesOnly: false,
@@ -274,6 +285,7 @@ test('should handle numeric module ids', () => {
         createModuleId: createModuleIdFactory(),
         dev: true,
         getRunModuleStatement,
+        globalPrefix: '',
         includeAsyncPaths: false,
         inlineSourceMap: false,
         modulesOnly: false,
@@ -322,6 +334,7 @@ test('outputs custom runModule statements', () => {
         dev: true,
         getRunModuleStatement: moduleId =>
           `export default require(${JSON.stringify(moduleId)}).default;`,
+        globalPrefix: '',
         includeAsyncPaths: false,
         inlineSourceMap: false,
         modulesOnly: false,
@@ -360,6 +373,7 @@ test('should add an inline source map to a very simple bundle', () => {
       createModuleId: filePath => path.basename(filePath),
       dev: true,
       getRunModuleStatement,
+      globalPrefix: '',
       includeAsyncPaths: false,
       inlineSourceMap: true,
       modulesOnly: false,
@@ -411,6 +425,7 @@ test('emits x_google_ignoreList based on shouldAddToIgnoreList', () => {
       createModuleId: filePath => path.basename(filePath),
       dev: true,
       getRunModuleStatement,
+      globalPrefix: '',
       includeAsyncPaths: false,
       inlineSourceMap: true,
       modulesOnly: false,
@@ -462,6 +477,7 @@ test('does not add polyfills when `modulesOnly` is used', () => {
         createModuleId: filePath => path.basename(filePath),
         dev: true,
         getRunModuleStatement,
+        globalPrefix: '',
         includeAsyncPaths: false,
         inlineSourceMap: false,
         modulesOnly: true,

packages/metro/src/DeltaBundler/Serializers/__tests__/getRamBundleInfo-test.js

@@ -94,6 +94,7 @@ test('should return the RAM bundle info', async () => {
           preloadedModules: {},
           ramGroups: [],
         }),
+        globalPrefix: '',
         includeAsyncPaths: false,
         inlineSourceMap: false,
         modulesOnly: false,
@@ -129,6 +130,7 @@ test('emits x_google_ignoreList based on shouldAddToIgnoreList', async () => {
           preloadedModules: {},
           ramGroups: [],
         }),
+        globalPrefix: '',
         includeAsyncPaths: false,
         inlineSourceMap: false,
         modulesOnly: false,
@@ -167,6 +169,7 @@ test('should use the preloadedModules and ramGroup configs to build a RAM bundle
       /* $FlowFixMe[incompatible-type] Natural Inference rollout. See
        * https://fburl.com/workplace/6291gfvu */
       getTransformOptions,
+      globalPrefix: '',
       includeAsyncPaths: false,
       inlineSourceMap: null,
       modulesOnly: false,

packages/metro/src/DeltaBundler/Serializers/baseJSBundle.js

@@ -59,6 +59,7 @@ export default function baseJSBundle(
       asyncRequireModulePath: options.asyncRequireModulePath,
       createModuleId: options.createModuleId,
       getRunModuleStatement: options.getRunModuleStatement,
+      globalPrefix: options.globalPrefix,
       inlineSourceMap: options.inlineSourceMap,
       runBeforeMainModule: options.runBeforeMainModule,
       runModule: options.runModule,

packages/metro/src/DeltaBundler/types.js

@@ -168,7 +168,11 @@ export type SerializerOptions = $ReadOnly<{
   asyncRequireModulePath: string,
   createModuleId: string => number,
   dev: boolean,
-  getRunModuleStatement: (number | string) => string,
+  getRunModuleStatement: (
+    moduleId: number | string,
+    globalPrefix: string,
+  ) => string,
+  globalPrefix: string,
   includeAsyncPaths: boolean,
   inlineSourceMap: ?boolean,
   modulesOnly: boolean,

packages/metro/src/Server.js

@@ -235,6 +235,7 @@ export default class Server {
       processModuleFilter: this._config.serializer.processModuleFilter,
       createModuleId: this._createModuleId,
       getRunModuleStatement: this._config.serializer.getRunModuleStatement,
+      globalPrefix: this._config.transformer.globalPrefix,
       dev: transformOptions.dev,
       includeAsyncPaths: graphOptions.lazy,
       projectRoot: this._config.projectRoot,
@@ -380,6 +381,7 @@ export default class Server {
       excludeSource: serializerOptions.excludeSource,
       getRunModuleStatement: this._config.serializer.getRunModuleStatement,
       getTransformOptions: this._config.transformer.getTransformOptions,
+      globalPrefix: this._config.transformer.globalPrefix,
       includeAsyncPaths: graphOptions.lazy,
       platform: transformOptions.platform,
       projectRoot: this._config.projectRoot,
@@ -1069,6 +1071,7 @@ export default class Server {
           processModuleFilter: this._config.serializer.processModuleFilter,
           createModuleId: this._createModuleId,
           getRunModuleStatement: this._config.serializer.getRunModuleStatement,
+          globalPrefix: this._config.transformer.globalPrefix,
           includeAsyncPaths: graphOptions.lazy,
           dev: transformOptions.dev,
           projectRoot: this._config.projectRoot,

packages/metro/src/lib/getAppendScripts.js

@@ -21,7 +21,8 @@ import nullthrows from 'nullthrows';
 type Options<T: number | string> = $ReadOnly<{
   asyncRequireModulePath: string,
   createModuleId: string => T,
-  getRunModuleStatement: T => string,
+  getRunModuleStatement: (moduleId: T, globalPrefix: string) => string,
+  globalPrefix: string,
   inlineSourceMap: ?boolean,
   runBeforeMainModule: $ReadOnlyArray<string>,
   runModule: boolean,
@@ -46,6 +47,7 @@ export default function getAppendScripts<T: number | string>(
       if (modules.some((module: Module<>) => module.path === path)) {
         const code = options.getRunModuleStatement(
           options.createModuleId(path),
+          options.globalPrefix,
         );
         output.push({
           path: `require-${path}`,