chore(microservice) tests for grpc cancelling - server side

Author: Michael Mrowetz

packages/microservices/test/server/server-grpc.spec.ts

@@ -1,7 +1,7 @@
 import { ServerGrpc } from '../../server/server-grpc';
 import { expect } from 'chai';
 import * as sinon from 'sinon';
-import { Observable } from 'rxjs';
+import { of } from 'rxjs';
 import { join } from 'path';
 import { InvalidGrpcPackageException } from '../../exceptions/invalid-grpc-package.exception';
 
@@ -161,6 +161,24 @@ describe('ServerGrpc', () => {
         await server.createStreamServiceMethod(native)(call, callback);
         expect(native.called).to.be.true;
         expect(call.addListener.calledWith('cancelled')).to.be.true;
+        expect(call.removeListener.calledWith('cancelled')).to.be.true;
+      });
+
+      it(`should close the result observable when receiving an 'cancelled' event from the client`, async () => {
+        let cancelCb: () => void;
+        const call = {
+          write: sinon.stub().onSecondCall().callsFake(() => cancelCb()),
+          end: sinon.spy(),
+          addListener: (name, cb) => cancelCb = cb,
+          removeListener: sinon.spy(),
+        };
+        const result$ = of(1, 2, 3);
+        const callback = sinon.spy();
+        const native = sinon.stub().returns(new Promise((resolve, reject) => resolve(result$)));
+
+        await server.createStreamServiceMethod(native)(call, callback);
+        expect(call.write.calledTwice).to.be.true;
+        expect(call.end.called).to.be.true;
       });
     });
   });