message: test(fromEventPattern): update test coverage for signal, optional removeHandler
diff: import {expect} from 'chai';
  +import * as sinon from 'sinon';
  import * as Rx from '../../dist/cjs/Rx';
  +import {noop} from '../../dist/cjs/util/noop';
  declare const rxTestScheduler: Rx.TestScheduler;
  declare const {hot, asDiagram, expectObservable, expectSubscriptions};
  @@ -58,6 +60,23 @@ describe('Observable.fromEventPattern', () => {
  expect(removeHandlerCalledWith).to.be.a('function');
  });
  + it('should work without optional removeHandler', () => {
  + const addHandler: (h: Function) => any = sinon.spy();
  + Observable.fromEventPattern(addHandler).subscribe(noop);
  +
  + expect(addHandler).calledOnce;
  + });
  +
  + it('should deliver return value of addHandler to removeHandler as signal', () => {
  + const expected = { signal: true};
  + const addHandler = () => expected;
  + const removeHandler = sinon.spy();
  + Observable.fromEventPattern(addHandler, removeHandler).subscribe(noop).unsubscribe();
  +
  + const call = removeHandler.getCall(0);
  + expect(call).calledWith(sinon.match.any, expected);
  + });
  +
  it('should send errors in addHandler down the error path', () => {
  Observable.fromEventPattern((h: any) => {
  throw 'bad';
  