import {jest, describe, it, expect} from 'bun:test';
import {Subject} from '../../src/observables';

describe('A Subject', () => {
  it('exposes the Subject value', () => {
    const subject = new Subject<string>('init-value');

    expect(subject.value).toBe('init-value');
  });

  it('updates the Subject value when set', () => {
    const subject = new Subject<string>('init-value');

    subject.value = 'some thing';

    expect(subject.value).toBe('some thing');
  });

  it('notifies subcribers when subscribing', () => {
    const subject = new Subject<string>('init-value');
    const listener = jest.fn() as (value: string) => void;

    subject.subscribe(listener);

    expect(listener).toHaveBeenCalledWith('init-value');
  });

  it('notifies subcribers when value changes', () => {
    const subject = new Subject<string>('init-value');
    const listener = jest.fn() as (value: string) => void;

    subject.subscribe(listener);

    subject.value = 'some thing';

    expect(listener).toHaveBeenCalledWith('some thing');
  });

  it('notifies all subcribers when value changes', () => {
    const subject = new Subject<string>('init-value');
    const listener1 = jest.fn() as (value: string) => void;
    const listener2 = jest.fn() as (value: string) => void;
    const listener3 = jest.fn() as (value: string) => void;

    subject.subscribe(listener1);
    subject.subscribe(listener2);
    subject.subscribe(listener3);

    subject.value = 'some thing';

    expect(listener1).toHaveBeenCalledWith('some thing');
    expect(listener2).toHaveBeenCalledWith('some thing');
    expect(listener3).toHaveBeenCalledWith('some thing');
  });
});