Handle renames/deletes of modules correctly

Reviewed By: cpojer

Differential Revision: D5845030

fbshipit-source-id: a33af56bf5a479768eaf64b42ec3251a724c0315

packages/metro-bundler/src/DeltaBundler/DeltaCalculator.js

@@ -167,6 +167,17 @@ class DeltaCalculator extends EventEmitter {
     type: string,
     filePath: string,
   }): mixed => {
+    // We do not want to keep track of deleted files, since this can cause
+    // issues when moving files (or even deleting files).
+    // The only issue with this approach is that the user removes a file that
+    // is needed, the bundler will still create a correct bundle (since it
+    // won't detect any modified file). Once we have our own dependency
+    // traverser in Delta Bundler this will be easy to fix.
+    if (type === 'delete') {
+      this._dependencies.delete(filePath);
+      return;
+    }
+
     this._modifiedFiles.add(filePath);
 
     // Notify users that there is a change in some of the bundle files. This

packages/metro-bundler/src/DeltaBundler/__tests__/DeltaCalculator-test.js

@@ -235,6 +235,21 @@ describe('DeltaCalculator', () => {
     expect(onChangeFile.mock.calls.length).toBe(0);
   });
 
+  it('should not emit an event when there is a file deleted', async () => {
+    jest.useFakeTimers();
+
+    const onChangeFile = jest.fn();
+    await deltaCalculator.getDelta();
+
+    deltaCalculator.on('delete', onChangeFile);
+
+    fileWatcher.emit('change', {eventsQueue: [{filePath: '/foo'}]});
+
+    jest.runAllTimers();
+
+    expect(onChangeFile.mock.calls.length).toBe(0);
+  });
+
   it('should retry to build the last delta after getting an error', async () => {
     await deltaCalculator.getDelta();