import createEventHub from '~/helpers/event_hub_factory'; const TEST_EVENT = 'foobar'; const TEST_EVENT_2 = 'testevent'; describe('event bus factory', () => { let eventBus; let handler; let otherHandlers; beforeEach(() => { eventBus = createEventHub(); handler = jest.fn(); otherHandlers = [jest.fn(), jest.fn()]; }); afterEach(() => { eventBus.dispose(); eventBus = null; }); describe('instance', () => { it.each` method ${'$on'} ${'$once'} ${'$off'} ${'$emit'} `('has $method method', ({ method }) => { expect(eventBus[method]).toEqual(expect.any(Function)); }); }); describe('$on', () => { beforeEach(() => { eventBus.$on(TEST_EVENT, handler); }); it('calls handler when event is emitted', () => { eventBus.$emit(TEST_EVENT); expect(handler).toHaveBeenCalledWith(); }); it('calls handler with multiple args', () => { eventBus.$emit(TEST_EVENT, 'arg1', 'arg2', 'arg3'); expect(handler).toHaveBeenCalledWith('arg1', 'arg2', 'arg3'); }); it('calls handler multiple times', () => { eventBus.$emit(TEST_EVENT, 'arg1', 'arg2', 'arg3'); eventBus.$emit(TEST_EVENT, 'arg1', 'arg2', 'arg3'); expect(handler).toHaveBeenCalledTimes(2); }); }); describe('$once', () => { beforeEach(() => { eventBus.$once(TEST_EVENT, handler); }); it('calls handler when event is emitted', () => { eventBus.$emit(TEST_EVENT); expect(handler).toHaveBeenCalled(); }); it('calls the handler only once when event is emitted multiple times', () => { eventBus.$emit(TEST_EVENT); eventBus.$emit(TEST_EVENT); expect(handler).toHaveBeenCalledTimes(1); }); describe('when the handler thows an error', () => { beforeEach(() => { handler = jest.fn().mockImplementation(() => { throw new Error(); }); eventBus.$once(TEST_EVENT, handler); }); it('calls off when event is emitted', () => { expect(() => { eventBus.$emit(TEST_EVENT); }).toThrow(); expect(() => { eventBus.$emit(TEST_EVENT); }).not.toThrow(); expect(handler).toHaveBeenCalledTimes(1); }); }); }); describe('$off', () => { beforeEach(() => { otherHandlers.forEach(x => eventBus.$on(TEST_EVENT, x)); eventBus.$on(TEST_EVENT, handler); }); it('can be called on event with no handlers', () => { expect(() => { eventBus.$off(TEST_EVENT_2); }).not.toThrow(); }); it('can be called on event with no handlers, with a handler', () => { expect(() => { eventBus.$off(TEST_EVENT_2, handler); }).not.toThrow(); }); it('with a handler, will no longer call that handler', () => { eventBus.$off(TEST_EVENT, handler); eventBus.$emit(TEST_EVENT); expect(handler).not.toHaveBeenCalled(); expect(otherHandlers.map(x => x.mock.calls.length)).toEqual(otherHandlers.map(() => 1)); }); it('without a handler, will no longer call any handlers', () => { eventBus.$off(TEST_EVENT); eventBus.$emit(TEST_EVENT); expect(handler).not.toHaveBeenCalled(); expect(otherHandlers.map(x => x.mock.calls.length)).toEqual(otherHandlers.map(() => 0)); }); }); describe('$emit', () => { beforeEach(() => { otherHandlers.forEach(x => eventBus.$on(TEST_EVENT_2, x)); eventBus.$on(TEST_EVENT, handler); }); it('only calls handlers for given type', () => { eventBus.$emit(TEST_EVENT, 'arg1'); expect(handler).toHaveBeenCalledWith('arg1'); expect(otherHandlers.map(x => x.mock.calls.length)).toEqual(otherHandlers.map(() => 0)); }); }); });