fix: add close method in fallbackServiceStub (#1182)

src/fallbackServiceStub.ts

@@ -70,7 +70,12 @@ export function generateServiceStub(
     ? window.fetch
     : (nodeFetch as unknown as NodeFetchType);
 
-  const serviceStub: FallbackServiceStub = {};
+  const serviceStub: FallbackServiceStub = {
+    // close method should close all cancel controllers. If this feature request in the future, we can have a cancelControllerFactory that tracks created cancel controllers, and abort them all in close method.
+    close: () => {
+      return {cancel: () => {}};
+    },
+  };
   for (const [rpcName, rpc] of Object.entries(rpcs)) {
     serviceStub[rpcName] = (
       request: {},

test/unit/grpc-fallback.ts

@@ -128,9 +128,10 @@ describe('createStub', () => {
     assert.strictEqual(typeof echoStub.echo, 'function');
     assert.strictEqual(typeof echoStub.pagedExpand, 'function');
     assert.strictEqual(typeof echoStub.wait, 'function');
+    assert.strictEqual(typeof echoStub.close, 'function');
 
-    // There should be 7 methods for the echo service
-    assert.strictEqual(Object.keys(echoStub).length, 7);
+    // There should be 7 methods for the echo service + 1 close method.
+    assert.strictEqual(Object.keys(echoStub).length, 8);
 
     // Each of the service methods should take 4 arguments (so that it works with createApiCall)
     assert.strictEqual(echoStub.echo.length, 4);
@@ -143,9 +144,10 @@ describe('createStub', () => {
     assert.strictEqual(typeof echoStub.echo, 'function');
     assert.strictEqual(typeof echoStub.collect, 'function');
     assert.strictEqual(typeof echoStub.chat, 'function');
+    assert.strictEqual(typeof echoStub.close, 'function');
 
-    // There should be 7 methods for the echo service
-    assert.strictEqual(Object.keys(echoStub).length, 7);
+    // There should be 7 methods for the echo service + 1 close method.
+    assert.strictEqual(Object.keys(echoStub).length, 8);
 
     // Each of the service methods should take 4 arguments (so that it works with createApiCall)
     assert.strictEqual(echoStub.echo.length, 4);
@@ -405,4 +407,13 @@ describe('grpc-fallback', () => {
     // @ts-ignore
     assert.strictEqual(createdAbortControllers[0].abortCalled, true);
   });
+
+  it('should have close method', done => {
+    // @ts-ignore
+    sinon.stub(nodeFetch, 'Promise').returns(Promise.resolve({}));
+    gaxGrpc.createStub(echoService, stubOptions).then(stub => {
+      stub.close({}, {}, {}, () => {});
+      done();
+    });
+  });
 });