Function createCall

packages/microservices/test/server/server-grpc.spec.ts:654–718

* A helper to create a repeated fixture to test streaming writes against.

()

         * A helper to create a repeated fixture to test streaming writes against.
         */
        async function createCall() {
          const emitter = new EventTarget();

          // If we write more than this number, the call will become unwritable.
          const highwaterMark = 2;
          let writeCounter = 0;

          // What has been "written" so far.
          const written: any[] = [];

          const drain = () => {
            writeCounter = 0;
            emitter.dispatchEvent(new Event('drain'));
          };

          const cancel = () => {
            emitter.dispatchEvent(new Event(CANCELLED_EVENT));
          };

          const call = {
            write: sinon.spy(value => {
              // Simulating a writable stream becoming overwhelmed.
              if (writeCounter++ < highwaterMark) {
                // We can write this value to the stream.
                written.push(value);
              }
              // But as soon as we pass the highwater mark, we can't write anymore.
              return writeCounter < highwaterMark;
            }),
            end: sinon.spy(() => {
              written.push('end');
            }),
            emit: sinon.spy(),
            request: sinon.spy(),
            metadata: sinon.spy(),
            sendMetadata: sinon.spy(),
            on: (name, cb) => {
              emitter.addEventListener(name, cb);
            },
            off: (name, cb) => {
              emitter.removeEventListener(name, cb);
            },
            fire: {
              drain,
              cancel,
            },
          };

          const callback = sinon.spy();

          const subject = new Subject<string>();
          const handlerResult = Promise.resolve(subject);
          const methodHandler = () => handlerResult;

          const serviceMethod = server.createRequestStreamMethod(
            methodHandler,
            true,
          );