fix(messageStream): remove call to destroy grpc stream

src/message-stream.ts

@@ -19,7 +19,7 @@ import {Gaxios} from 'gaxios';
 import {ClientStub} from 'google-gax';
 import {ClientDuplexStream, Metadata, ServiceError, status, StatusObject} from 'grpc';
 import * as isStreamEnded from 'is-stream-ended';
-import {Duplex, PassThrough} from 'stream';
+import {PassThrough} from 'stream';
 
 import {PullResponse, Subscriber} from './subscriber';
 
@@ -109,29 +109,6 @@ export class ChannelError extends Error implements ServiceError {
   }
 }
 
-/**
- * Ponyfill for destroying streams.
- *
- * @private
- *
- * @param {stream} stream The stream to destroy.
- * @param {error?} err Error to emit.
- */
-export function destroy(stream: Duplex, err?: Error): void {
-  const nativeDestroy = Duplex.prototype.destroy;
-
-  if (typeof nativeDestroy === 'function') {
-    return nativeDestroy.call(stream, err);
-  }
-
-  process.nextTick(() => {
-    if (err) {
-      stream.emit('error', err);
-    }
-    stream.emit('close');
-  });
-}
-
 /**
  * @typedef {object} MessageStreamOptions
  * @property {number} [highWaterMark=0] Configures the Buffer level for all
@@ -197,7 +174,16 @@ export class MessageStream extends PassThrough {
       stream.cancel();
     }
 
-    return destroy(this, err);
+    if (typeof super.destroy === 'function') {
+      return super.destroy(err);
+    }
+
+    process.nextTick(() => {
+      if (err) {
+        this.emit('error', err);
+      }
+      this.emit('close');
+    });
   }
   /**
    * Adds a StreamingPull stream to the combined stream.
@@ -329,7 +315,6 @@ export class MessageStream extends PassThrough {
    */
   private _onStatus(stream: PullStream, status: StatusObject): void {
     if (this.destroyed) {
-      destroy(stream);
       return;
     }
 

test/message-stream.ts

@@ -41,21 +41,18 @@ interface StreamOptions {
   highWaterMark?: number;
 }
 
-class FakeDuplex extends Duplex {
-  destroy(err?: Error): void {
-    if (super.destroy) {
-      return super.destroy(err);
-    }
-    destroy(this, err);
-  }
-}
-
 class FakePassThrough extends PassThrough {
   options: StreamOptions;
   constructor(options: StreamOptions) {
     super(options);
     this.options = options;
   }
+  destroy(err?: Error): void {
+    if (super.destroy) {
+      return super.destroy(err);
+    }
+    destroy(this, err);
+  }
 }
 
 class FakeGrpcStream extends Duplex {
@@ -136,10 +133,9 @@ describe('MessageStream', () => {
   let messageStream;
 
   before(() => {
-    MessageStream =
-        proxyquire('../src/message-stream.js', {
-          'stream': {Duplex: FakeDuplex, PassThrough: FakePassThrough}
-        }).MessageStream;
+    MessageStream = proxyquire('../src/message-stream.js', {
+                      'stream': {PassThrough: FakePassThrough}
+                    }).MessageStream;
   });
 
   beforeEach(() => {
@@ -257,7 +253,7 @@ describe('MessageStream', () => {
 
   describe('destroy', () => {
     it('should noop if already destroyed', done => {
-      const stub = sandbox.stub(FakeDuplex.prototype, 'destroy')
+      const stub = sandbox.stub(FakePassThrough.prototype, 'destroy')
                        .callsFake(function(this: Duplex) {
                          if (this === messageStream) {
                            done();
@@ -309,13 +305,13 @@ describe('MessageStream', () => {
       let destroy;
 
       before(() => {
-        destroy = FakeDuplex.prototype.destroy;
+        destroy = FakePassThrough.prototype.destroy;
         // tslint:disable-next-line no-any
-        FakeDuplex.prototype.destroy = (false as any);
+        FakePassThrough.prototype.destroy = (false as any);
       });
 
       after(() => {
-        FakeDuplex.prototype.destroy = destroy;
+        FakePassThrough.prototype.destroy = destroy;
       });
 
       it('should emit close', done => {
@@ -446,20 +442,6 @@ describe('MessageStream', () => {
     });
 
     describe('on status', () => {
-      it('should destroy the stream if the message stream is destroyed',
-         done => {
-           const [stream] = client.streams;
-           const stub = sandbox.stub(FakeDuplex.prototype, 'destroy')
-                            .callsFake(function(this: Duplex) {
-                              if (this === stream) {
-                                done();
-                              }
-                            });
-
-           messageStream.destroy();
-           stream.emit('status', {});
-         });
-
       it('should wait for end to fire before creating a new stream', done => {
         const [stream] = client.streams;
         const expectedCount = stream.listenerCount('end') + 1;