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

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

    expect(readOnlySubject.value).toBe(`init-value`);
  });

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

    subject.value = 'some thing';

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

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

    readOnlySubject.subscribe(listener);

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

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

    readOnlySubject.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 readOnlySubject = new ReadOnlySubject(subject);
    const listener1 = jest.fn() as (value: string) => void;
    const listener2 = jest.fn() as (value: string) => void;
    const listener3 = jest.fn() as (value: string) => void;

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

    subject.value = 'some thing';

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