Expose the asyncRequireModulePath param

Reviewed By: mjesun

Differential Revision: D7709569

fbshipit-source-id: 871dd9c178b1e5c81163558201ef983315561211

packages/metro/src/Config.js

@@ -67,6 +67,12 @@ export type ConfigT = {
    */
   getBlacklistRE(): RegExp,
 
+  /**
+   * Specify an implementation module to load async import modules (for
+   * splitting).
+   */
+  getAsyncRequireModulePath(): string,
+
   /**
    * Specify whether or not to enable Babel's behavior for looking up .babelrc
    * files. If false, only the .babelrc file (if one exists) in the main project
@@ -175,6 +181,7 @@ const DEFAULT = ({
   cacheStores: [],
   cacheVersion: '1.0',
   dynamicDepsInPackages: 'throwAtRuntime',
+  getAsyncRequireModulePath: () => 'metro/src/lib/bundle-modules/asyncRequire',
   getAssetExts: () => [],
   getBlacklistRE: () => blacklist(),
   getEnableBabelRCLookup: () => true,

packages/metro/src/index.js

@@ -110,6 +110,7 @@ async function runMetro({
     projectRoots: finalProjectRoots,
   });
   const serverOptions: ServerOptions = {
+    asyncRequireModulePath: normalizedConfig.getAsyncRequireModulePath(),
     assetExts: normalizedConfig.assetTransforms ? [] : assetExts,
     assetRegistryPath: normalizedConfig.assetRegistryPath,
     blacklistRE: normalizedConfig.getBlacklistRE(),

packages/metro/src/shared/types.flow.js

@@ -78,7 +78,7 @@ export type Options = {|
   // TODO: Remove this option below (T23793920)
   assetTransforms?: boolean,
   assetExts?: Array<string>,
-  +asyncRequireModulePath?: string,
+  +asyncRequireModulePath: string,
   +assetRegistryPath: string,
   blacklistRE?: RegExp,
   cacheStores: $ReadOnlyArray<CacheStore<TransformedCode>>,