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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));
});
});
});
|
