Add integration tests for virtual-prefix URL routing (#1706)

Summary:

Adds integration tests for `[metro-project]` and `[metro-watchFolders]` virtual URL prefixes: bundle requests, out-of-bounds index 404, and asset serving.

Removes Server unit tests that tested private methods (`_resolveWatchFolderPrefix`, `_getEntryPointAbsolutePath`) directly. The behaviours they covered are now tested end-to-end by the new integration tests and will also be covered by `ProjectRouteMap` unit tests in the next diff.

All tests pass without any production code changes.

Reviewed By: huntie

Differential Revision: D104259281

Author: motiz88

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

@@ -1436,87 +1436,4 @@ describe('processRequest', () => {
       },
     );
   });
-
-  describe('watchFolder prefix resolution', () => {
-    let watchFolderServer: $FlowFixMe;
-
-    beforeEach(() => {
-      watchFolderServer = new Server(
-        mergeConfig(getDefaultValues('/'), {
-          projectRoot: '/project',
-          watchFolders: ['/project', '/external/packages'],
-          resolver: {blockList: []},
-          cacheVersion: '',
-          serializer: {
-            getRunModuleStatement: moduleId =>
-              `require(${JSON.stringify(moduleId)});`,
-            polyfillModuleNames: [],
-            getModulesRunBeforeMainModule: () => ['InitializeCore'],
-          },
-          reporter: require('../../lib/reporting').nullReporter,
-        } as InputConfigT),
-      );
-    });
-
-    test('resolves [metro-watchFolders]/N/ prefix against the Nth watch folder', () => {
-      expect(
-        watchFolderServer._resolveWatchFolderPrefix(
-          './[metro-watchFolders]/1/expo-router/entry',
-        ),
-      ).toEqual({
-        rootDir: '/external/packages',
-        filePath: './expo-router/entry',
-      });
-    });
-
-    test('resolves [metro-watchFolders]/0/ prefix against the first watch folder', () => {
-      expect(
-        watchFolderServer._resolveWatchFolderPrefix(
-          './[metro-watchFolders]/0/app/index',
-        ),
-      ).toEqual({
-        rootDir: '/project',
-        filePath: './app/index',
-      });
-    });
-
-    test('resolves [metro-project]/ prefix against projectRoot', () => {
-      expect(
-        watchFolderServer._resolveWatchFolderPrefix(
-          './[metro-project]/src/App',
-        ),
-      ).toEqual({
-        rootDir: '/project',
-        filePath: './src/App',
-      });
-    });
-
-    test('returns null for paths without a recognized prefix', () => {
-      expect(
-        watchFolderServer._resolveWatchFolderPrefix('./mybundle'),
-      ).toBeNull();
-    });
-
-    test('returns null for out-of-bounds watchFolder index', () => {
-      expect(
-        watchFolderServer._resolveWatchFolderPrefix(
-          './[metro-watchFolders]/99/mybundle',
-        ),
-      ).toBeNull();
-    });
-
-    test('_getEntryPointAbsolutePath resolves prefixed entry against the corresponding watch folder', () => {
-      expect(
-        watchFolderServer._getEntryPointAbsolutePath(
-          './[metro-watchFolders]/1/expo-router/entry',
-        ),
-      ).toBe('/external/packages/expo-router/entry');
-    });
-
-    test('_getEntryPointAbsolutePath resolves non-prefixed entry against server root', () => {
-      expect(watchFolderServer._getEntryPointAbsolutePath('./mybundle')).toBe(
-        '/project/mybundle',
-      );
-    });
-  });
 });

packages/metro/src/integration_tests/__tests__/build-test.js

@@ -118,6 +118,41 @@ test('allows specifying paths to save bundle and maps', async () => {
   );
 });
 
+// $FlowFixMe[prop-missing] - test.failing is not in Flow's Jest types
+test.failing(
+  'builds a bundle from a file in a directory literally named [metro-project]',
+  async () => {
+    const config = await Metro.loadConfig({
+      config: require.resolve('../metro.config.js'),
+    });
+
+    const result = await Metro.runBuild(config, {
+      entry: './[metro-project]/LiteralDir.js',
+    });
+
+    expect(execBundle(result.code)).toBe('from-literal-dir');
+  },
+);
+
+// $FlowFixMe[prop-missing] - test.failing is not in Flow's Jest types
+test.failing(
+  'runBuild resolves entry against projectRoot, not unstable_serverRoot',
+  async () => {
+    const baseConfig = await Metro.loadConfig({
+      config: require.resolve('../metro.config.js'),
+    });
+    const config = MetroConfig.mergeConfig(baseConfig, {
+      server: {unstable_serverRoot: path.resolve(INPUT_PATH, '..')},
+    });
+
+    const result = await Metro.runBuild(config, {
+      entry: 'TestBundle.js',
+    });
+
+    expect(execBundle(result.code)).toBeDefined();
+  },
+);
+
 test('(unstable) allows specifying a transform profile', async () => {
   const config = await Metro.loadConfig({
     config: require.resolve('../metro.config.js'),

packages/metro/src/integration_tests/__tests__/rambundle-test.js

@@ -19,32 +19,46 @@ const vm = require('vm');
 
 jest.setTimeout(30 * 1000);
 
-test('builds and executes a RAM bundle', async () => {
-  const config = await Metro.loadConfig({
+let config;
+
+beforeAll(async () => {
+  config = await Metro.loadConfig({
     config: require.resolve('../metro.config.js'),
   });
-  const bundlePath = path.join(os.tmpdir(), 'rambundle.js');
+});
 
+async function buildAndExecRamBundle(entry: string): mixed {
+  const bundlePath = path.join(os.tmpdir(), `rambundle-${Date.now()}.js`);
   try {
     await Metro.runBuild(config, {
-      entry: 'TestBundle.js',
+      entry,
       output: ramBundleOutput,
       out: bundlePath,
     });
 
     const bundleBuffer = fs.readFileSync(bundlePath);
     const parser = new RamBundleParser(bundleBuffer);
 
-    // Create a context with a global nativeRequire function, which reads the
-    // module code from the RAM bundle and injects it into the VM.
     const context = vm.createContext({
       nativeRequire(id) {
         vm.runInContext(parser.getModule(id), context);
       },
     });
 
-    expect(vm.runInContext(parser.getStartupCode(), context)).toMatchSnapshot();
+    return vm.runInContext(parser.getStartupCode(), context);
   } finally {
-    fs.unlinkSync(bundlePath);
+    if (fs.existsSync(bundlePath)) {
+      fs.unlinkSync(bundlePath);
+    }
   }
+}
+
+test('builds and executes a RAM bundle', async () => {
+  expect(await buildAndExecRamBundle('TestBundle.js')).toMatchSnapshot();
+});
+
+test('rejects [metro-project] virtual prefix in runBuild entry', async () => {
+  await expect(
+    buildAndExecRamBundle('./[metro-project]/TestBundle.js'),
+  ).rejects.toThrow('was not found');
 });

packages/metro/src/integration_tests/__tests__/server-test.js

@@ -122,6 +122,71 @@ describe('Metro development server serves bundles via HTTP', () => {
     );
   });
 
+  test('should serve bundles with [metro-watchFolders] entry point', async () => {
+    expect(
+      await downloadAndExec(
+        '/[metro-watchFolders]/1/metro/src/integration_tests/basic_bundle/TestBundle.bundle?platform=ios&dev=true&minify=false',
+      ),
+    ).toBeDefined();
+  });
+
+  test('should serve bundles with [metro-project] entry point', async () => {
+    expect(
+      await downloadAndExec(
+        '/[metro-project]/TestBundle.bundle?platform=ios&dev=true&minify=false',
+      ),
+    ).toBeDefined();
+  });
+
+  test('[metro-project] source map resolves same modules as non-prefixed', async () => {
+    const directResponse = await fetchAndClose(
+      'http://localhost:' +
+        httpServer.address().port +
+        '/TestBundle.map?platform=ios&dev=true&minify=false',
+    );
+    const prefixedResponse = await fetchAndClose(
+      'http://localhost:' +
+        httpServer.address().port +
+        '/[metro-project]/TestBundle.map?platform=ios&dev=true&minify=false',
+    );
+    expect(directResponse.ok).toBe(true);
+    expect(prefixedResponse.ok).toBe(true);
+    const directMap = await directResponse.json();
+    const prefixedMap = await prefixedResponse.json();
+    expect([...prefixedMap.sources].sort()).toEqual(
+      [...directMap.sources].sort(),
+    );
+  });
+
+  test('[metro-watchFolders] source map resolves same modules as non-prefixed', async () => {
+    const directResponse = await fetchAndClose(
+      'http://localhost:' +
+        httpServer.address().port +
+        '/TestBundle.map?platform=ios&dev=true&minify=false',
+    );
+    const watchFolderResponse = await fetchAndClose(
+      'http://localhost:' +
+        httpServer.address().port +
+        '/[metro-watchFolders]/1/metro/src/integration_tests/basic_bundle/TestBundle.map?platform=ios&dev=true&minify=false',
+    );
+    expect(directResponse.ok).toBe(true);
+    expect(watchFolderResponse.ok).toBe(true);
+    const directMap = await directResponse.json();
+    const watchFolderMap = await watchFolderResponse.json();
+    expect([...watchFolderMap.sources].sort()).toEqual(
+      [...directMap.sources].sort(),
+    );
+  });
+
+  test('responds with 404 for [metro-watchFolders] with out-of-bounds index', async () => {
+    const response = await fetchAndClose(
+      'http://localhost:' +
+        httpServer.address().port +
+        '/[metro-watchFolders]/99/TestBundle.bundle?platform=ios&dev=true&minify=false',
+    );
+    expect(response.status).toBe(404);
+  });
+
   test('responds with 404 when the bundle cannot be resolved', async () => {
     const response = await fetchAndClose(
       'http://localhost:' + httpServer.address().port + '/doesnotexist.bundle',

packages/metro/src/integration_tests/basic_bundle/[metro-project]/LiteralDir.js

@@ -0,0 +1,11 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow strict-local
+ * @format
+ */
+
+module.exports = 'from-literal-dir';