Fix HmrServer crash when entry point uses virtual URL prefix (facebook#1709)

Summary:

D102004228 added support for serving bundles from `Server` with the handling `[metro-watchFolders]/<N>/...` or `[metro-project]/...` virtual URL prefixes, but did not add the same support in `HmrServer`.

Here, `HmrServer` constructs its own `ProjectRouteMap` to match `Server`'s behaviour exactly.

Changelog:

* **[Fix]:** Prevent HMR crash on `[metro-watchFolders]` or `[metro-project]` URLs

Differential Revision: D104223071

Author: motiz88

packages/metro/src/HmrServer.js

@@ -28,6 +28,7 @@ import debounceAsyncQueue from './lib/debounceAsyncQueue';
 import formatBundlingError from './lib/formatBundlingError';
 import getGraphId from './lib/getGraphId';
 import parseBundleOptionsFromBundleRequestUrl from './lib/parseBundleOptionsFromBundleRequestUrl';
+import ProjectRouteMap from './lib/ProjectRouteMap';
 import splitBundleOptions from './lib/splitBundleOptions';
 import * as transformHelpers from './lib/transformHelpers';
 import {Logger} from 'metro-core';
@@ -71,6 +72,7 @@ export default class HmrServer<TClient extends Client> {
   _bundler: IncrementalBundler;
   _createModuleId: (path: string) => number;
   _clientGroups: Map<RevisionId, ClientGroup>;
+  _routeMap: ProjectRouteMap;
 
   constructor(
     bundler: IncrementalBundler,
@@ -81,6 +83,7 @@ export default class HmrServer<TClient extends Client> {
     this._bundler = bundler;
     this._createModuleId = createModuleId;
     this._clientGroups = new Map();
+    this._routeMap = new ProjectRouteMap(config);
   }
 
   onClientConnect: (
@@ -121,19 +124,18 @@ export default class HmrServer<TClient extends Client> {
       transformOptions.platform,
       resolverOptions,
     );
-    const resolvedEntryFilePath = resolutionFn(
-      (this._config.server.unstable_serverRoot ?? this._config.projectRoot) +
-        '/.',
-      {
-        name: entryFile,
-        data: {
-          key: entryFile,
-          asyncType: null,
-          isESMImport: false,
-          locs: [],
-        },
+    const absolutePath = this._routeMap.filePathOfUrlDecodedPathname(entryFile);
+    const rootDir = absolutePath != null ? '/' : this._routeMap.serverRootDir;
+    const resolvedEntryFile = absolutePath ?? entryFile;
+    const resolvedEntryFilePath = resolutionFn(rootDir + '/.', {
+      name: resolvedEntryFile,
+      data: {
+        key: resolvedEntryFile,
+        asyncType: null,
+        isESMImport: false,
+        locs: [],
       },
-    ).filePath;
+    }).filePath;
     const graphId = getGraphId(resolvedEntryFilePath, transformOptions, {
       resolverOptions,
       shallow: graphOptions.shallow,
@@ -379,8 +381,7 @@ export default class HmrServer<TClient extends Client> {
         createModuleId: this._createModuleId,
         includeAsyncPaths: group.graphOptions.lazy,
         projectRoot: this._config.projectRoot,
-        serverRoot:
-          this._config.server.unstable_serverRoot ?? this._config.projectRoot,
+        serverRoot: this._routeMap.serverRootDir,
       });
 
       logger?.point('serialize_end');

packages/metro/src/__tests__/HmrServer-test.js

@@ -130,6 +130,7 @@ describe('HmrServer', () => {
         unstable_allowRequireContext: false,
       },
       resolver: {platforms: []},
+      watchFolders: ['/external/node_modules'],
       server: {
         rewriteRequestUrl(requrl) {
           const rewritten = requrl.replace(
@@ -650,6 +651,60 @@ describe('HmrServer', () => {
     ]);
   });
 
+  test('should resolve [metro-watchFolders] prefix in entry point', async () => {
+    await connect(
+      '/hot?bundleEntry=./[metro-watchFolders]/0/expo-router/entry.js&platform=ios',
+    );
+
+    expect(getRevisionByGraphIdMock).toBeCalledWith(
+      getGraphId(
+        '/external/node_modules/expo-router/entry.js',
+        {
+          customTransformOptions: {},
+          dev: true,
+          minify: false,
+          platform: 'ios',
+          type: 'module',
+          unstable_transformProfile: 'default',
+        },
+        {
+          shallow: false,
+          lazy: false,
+          unstable_allowRequireContext: false,
+          resolverOptions: {
+            dev: true,
+          },
+        },
+      ),
+    );
+  });
+
+  test('should resolve [metro-project] prefix in entry point', async () => {
+    await connect('/hot?bundleEntry=./[metro-project]/src/App.js&platform=ios');
+
+    expect(getRevisionByGraphIdMock).toBeCalledWith(
+      getGraphId(
+        '/root/src/App.js',
+        {
+          customTransformOptions: {},
+          dev: true,
+          minify: false,
+          platform: 'ios',
+          type: 'module',
+          unstable_transformProfile: 'default',
+        },
+        {
+          shallow: false,
+          lazy: false,
+          unstable_allowRequireContext: false,
+          resolverOptions: {
+            dev: true,
+          },
+        },
+      ),
+    );
+  });
+
   test('should return error messages when there is a transform error', async () => {
     jest.useRealTimers();
     const sendMessage = jest.fn();

packages/metro/types/HmrServer.d.ts

@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  *
  * @noformat
- * @generated SignedSource<<ab4c245134631e14db114a9d49da79d1>>
+ * @generated SignedSource<<81f86f56137b8992ca4e56f39628d548>>
  *
  * This file was translated from Flow by scripts/generateTypeScriptDefinitions.js
  * Original file: packages/metro/src/HmrServer.js
@@ -25,6 +25,8 @@ import type {
   HmrUpdateMessage,
 } from 'metro-runtime/src/modules/types';
 
+import ProjectRouteMap from './lib/ProjectRouteMap';
+
 export type Client = {
   optedIntoHMR: boolean;
   revisionIds: Array<RevisionId>;
@@ -51,6 +53,7 @@ declare class HmrServer<TClient extends Client> {
   _bundler: IncrementalBundler;
   _createModuleId: (path: string) => number;
   _clientGroups: Map<RevisionId, ClientGroup>;
+  _routeMap: ProjectRouteMap;
   constructor(
     bundler: IncrementalBundler,
     createModuleId: (path: string) => number,