jakciehan
99 lines
2.9 KiB
TypeScript
99 lines
2.9 KiB
TypeScript
import { EventBus } from '@common/EventBus';
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describe('EventBus', () => {
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let bus: EventBus;
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beforeEach(() => {
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bus = new EventBus();
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});
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it('delivers emitted payload to on() subscribers', () => {
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const spy = jest.fn();
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bus.on<number>('hit', spy);
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bus.emit('hit', 42);
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expect(spy).toHaveBeenCalledWith(42);
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});
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it('ignores duplicate subscriptions of the same handler', () => {
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const spy = jest.fn();
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bus.on('hit', spy);
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bus.on('hit', spy);
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bus.emit('hit', 1);
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expect(spy).toHaveBeenCalledTimes(1);
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expect(bus.listenerCount('hit')).toBe(1);
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});
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it('fires once() handlers exactly one time', () => {
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const spy = jest.fn();
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bus.once('hit', spy);
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bus.emit('hit', 1);
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bus.emit('hit', 2);
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expect(spy).toHaveBeenCalledTimes(1);
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expect(bus.listenerCount('hit')).toBe(0);
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});
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it('off(event, fn) removes only that handler', () => {
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const a = jest.fn();
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const b = jest.fn();
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bus.on('hit', a);
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bus.on('hit', b);
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bus.off('hit', a);
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bus.emit('hit', 1);
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expect(a).not.toHaveBeenCalled();
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expect(b).toHaveBeenCalledTimes(1);
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});
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it('off(event) clears all handlers of that event', () => {
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const a = jest.fn();
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const b = jest.fn();
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bus.on('hit', a);
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bus.on('hit', b);
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bus.off('hit');
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bus.emit('hit', 1);
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expect(a).not.toHaveBeenCalled();
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expect(b).not.toHaveBeenCalled();
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expect(bus.listenerCount('hit')).toBe(0);
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});
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it('isolates exceptions — one bad listener does not break fan-out', () => {
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const err = jest.fn();
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bus.setErrorHook(err);
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const good = jest.fn();
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bus.on('hit', () => {
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throw new Error('boom');
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});
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bus.on('hit', good);
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bus.emit('hit', 1);
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expect(good).toHaveBeenCalledTimes(1);
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expect(err).toHaveBeenCalledTimes(1);
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expect(err.mock.calls[0][0]).toBe('hit');
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});
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it('emit on an unknown event is a no-op', () => {
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expect(() => bus.emit('ghost', 1)).not.toThrow();
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});
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it('clear() drops every handler of every event', () => {
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bus.on('a', () => {});
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bus.on('b', () => {});
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bus.clear();
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expect(bus.listenerCount('a')).toBe(0);
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expect(bus.listenerCount('b')).toBe(0);
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});
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it('supports off for a non-existent handler without error', () => {
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const spy = jest.fn();
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bus.off('hit', spy);
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expect(bus.listenerCount('hit')).toBe(0);
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});
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it('handles a once-handler unsubscribing itself during emit', () => {
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const calls: number[] = [];
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bus.once<number>('tick', (n) => calls.push(n));
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bus.on<number>('tick', (n) => calls.push(n * 10));
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bus.emit('tick', 1);
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bus.emit('tick', 2);
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expect(calls).toEqual([1, 10, 20]);
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});
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});
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