metro-file-map: Extract mocks handling into nullable MockMap

packages/metro-file-map/src/__tests__/index-test.js

@@ -742,6 +742,36 @@ describe('FileMap', () => {
     expect(fs.readFileSync.mock.calls.length).toBe(5);
   });
 
+  test('builds a mock map if mocksPattern is non-null', async () => {
+    const pathToMock = path.join(
+      '/',
+      'project',
+      'fruits1',
+      '__mocks__',
+      'Blueberry.js',
+    );
+    mockFs[pathToMock] = '/* empty */';
+
+    const {mockMap} = await new FileMap({
+      mocksPattern: '__mocks__',
+      throwOnModuleCollision: true,
+      ...defaultConfig,
+    }).build();
+
+    expect(mockMap).not.toBeNull();
+    expect(mockMap.getMockModule('Blueberry')).toEqual(pathToMock);
+  });
+
+  test('returns null mockMap if mocksPattern is empty', async () => {
+    const {mockMap} = await new FileMap({
+      mocksPattern: '',
+      throwOnModuleCollision: true,
+      ...defaultConfig,
+    }).build();
+
+    expect(mockMap).toBeNull();
+  });
+
   test('warns on duplicate mock files', async () => {
     expect.assertions(1);
 
@@ -1341,7 +1371,6 @@ describe('FileMap', () => {
           enableHastePackages: true,
           filePath: path.join('/', 'project', 'fruits', 'Banana.js'),
           hasteImplModulePath: undefined,
-          readLink: false,
           rootDir: path.join('/', 'project'),
         },
       ],
@@ -1353,7 +1382,6 @@ describe('FileMap', () => {
           enableHastePackages: true,
           filePath: path.join('/', 'project', 'fruits', 'Pear.js'),
           hasteImplModulePath: undefined,
-          readLink: false,
           rootDir: path.join('/', 'project'),
         },
       ],
@@ -1365,7 +1393,6 @@ describe('FileMap', () => {
           enableHastePackages: true,
           filePath: path.join('/', 'project', 'fruits', 'Strawberry.js'),
           hasteImplModulePath: undefined,
-          readLink: false,
           rootDir: path.join('/', 'project'),
         },
       ],
@@ -1377,7 +1404,6 @@ describe('FileMap', () => {
           enableHastePackages: true,
           filePath: path.join('/', 'project', 'fruits', '__mocks__', 'Pear.js'),
           hasteImplModulePath: undefined,
-          readLink: false,
           rootDir: path.join('/', 'project'),
         },
       ],
@@ -1389,7 +1415,6 @@ describe('FileMap', () => {
           enableHastePackages: true,
           filePath: path.join('/', 'project', 'vegetables', 'Melon.js'),
           hasteImplModulePath: undefined,
-          readLink: false,
           rootDir: path.join('/', 'project'),
         },
       ],

packages/metro-file-map/src/__tests__/worker-test.js

@@ -54,19 +54,6 @@ jest.mock('fs', () => {
       }
       throw new Error(`Cannot read path '${path}'.`);
     }),
-    promises: {
-      readlink: jest.fn(async path => {
-        const entry = mockFs[path];
-        if (entry) {
-          if (typeof entry.link === 'string') {
-            return entry.link;
-          } else {
-            throw new Error('Tried to call readlink on a non-symlink');
-          }
-        }
-        throw new Error(`Cannot read path '${path}'.`);
-      }),
-    },
   };
 });
 
@@ -240,26 +227,6 @@ describe('worker', () => {
     expect(fs.readFile).not.toHaveBeenCalled();
   });
 
-  test('calls readLink and returns symlink target when readLink=true', async () => {
-    expect(
-      await worker({
-        computeDependencies: false,
-        filePath: path.join('/project', 'fruits', 'LinkToStrawberry.js'),
-        readLink: true,
-        rootDir,
-      }),
-    ).toEqual({
-      dependencies: undefined,
-      id: undefined,
-      module: undefined,
-      sha1: undefined,
-      symlinkTarget: path.join('.', 'Strawberry.js'),
-    });
-
-    expect(fs.readFileSync).not.toHaveBeenCalled();
-    expect(fs.promises.readlink).toHaveBeenCalled();
-  });
-
   test('can be loaded directly without transpilation', async () => {
     const code = await jest
       .requireActual('fs')

packages/metro-file-map/src/flow-types.js

@@ -43,7 +43,7 @@ export type BuildParameters = $ReadOnly<{
 export type BuildResult = {
   fileSystem: FileSystem,
   hasteMap: HasteMap,
-  mockMap: MockMap,
+  mockMap: ?MockMap,
 };
 
 export type CacheData = $ReadOnly<{
@@ -326,7 +326,6 @@ export type WorkerMessage = $ReadOnly<{
   computeSha1: boolean,
   dependencyExtractor?: ?string,
   enableHastePackages: boolean,
-  readLink: boolean,
   rootDir: string,
   filePath: string,
   hasteImplModulePath?: ?string,
@@ -337,5 +336,4 @@ export type WorkerMetadata = $ReadOnly<{
   id?: ?string,
   module?: ?HasteMapItemMetaData,
   sha1?: ?string,
-  symlinkTarget?: ?string,
 }>;