import { InMemoryPubSub } from './in-memory-pub-sub';

const CHANNEL_FOO = 'foo';

describe('in-memory pubsub', () => {
  it('should receive message from subscription', () => {
    const pubSub = new InMemoryPubSub<string>();
    const callback = jest.fn();
    pubSub.subscribe(CHANNEL_FOO, callback);
    const payload = 'hello world';
    pubSub.publish(CHANNEL_FOO, payload);
    expect(callback).toHaveBeenCalledWith(payload);
  });

  it('should receive message from two subscriptions', () => {
    const pubSub = new InMemoryPubSub<string>();
    const callback1 = jest.fn();
    const callback2 = jest.fn();
    pubSub.subscribe(CHANNEL_FOO, callback1);
    pubSub.subscribe(CHANNEL_FOO, callback2);
    const payload = 'hello world';
    pubSub.publish(CHANNEL_FOO, payload);
    expect(callback1).toHaveBeenCalledWith(payload);
    expect(callback2).toHaveBeenCalledWith(payload);
  });

  it('should unsubscribe', () => {
    const pubSub = new InMemoryPubSub<string>();
    const callback = jest.fn();
    pubSub.subscribe(CHANNEL_FOO, callback);
    pubSub.unsubscribeAll(CHANNEL_FOO);
    const payload = 'hello world';
    pubSub.publish(CHANNEL_FOO, payload);
    expect(callback).not.toHaveBeenCalled();
  });

  it('should ignore extra unsubscribe', () => {
    const pubSub = new InMemoryPubSub<string>();
    const callback = jest.fn();
    pubSub.subscribe(CHANNEL_FOO, callback);
    pubSub.unsubscribeAll(CHANNEL_FOO);
    pubSub.unsubscribeAll(CHANNEL_FOO); // do nothing
    const payload = 'hello world';
    pubSub.publish(CHANNEL_FOO, payload);
    expect(callback).not.toHaveBeenCalled();
  });
});