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