stm-5.js

tests.js

const lib = require('../index');

// ------------------------------------
// -------------- HELPERS -------------
// ------------------------------------

const EFFECT_STATUS = {
  idle: 'IDLE',
  req: 'REQUEST',
  res: 'RESPONSE',
  err: 'ERROR',
};

const createEffect = request => {
  const node = lib.createNode({
    // `reset` - call when initiate
    reset: () => ({ status: EFFECT_STATUS.idle, payload: null, error: null }),
    req: payload => ({ status: EFFECT_STATUS.req, payload, error: null }),
    res: payload => ({ status: EFFECT_STATUS.res, payload, error: null }),
    err: error => ({ status: EFFECT_STATUS.err, payload: null, error }),
  });

  const effect = async payload => {
    node.req(payload);
    try {
      const response = await request(payload);

      if (node.get().status !== EFFECT_STATUS.req) {
        /* concurrency */ return;
      } else {
        node.res(response);
      }
    } catch (error) {
      node.err(error);
    }
  };

  // `toString` return unique node id with dynamic counter
  // it is mean you can use many times `({ [effect]: some1, [effect]: some2 })`
  // and `[effect]` properties will difference
  effect.toString = node.toString();

  effect.on = predicate => mod => ({
    [effect]: {
      if: predicate,
      mod,
    },
  });

  effect.onResponse = effect.on(({ status }) => status === EFFECT_STATUS.res);
  effect.onRequest = effect.on(({ status }) => status === EFFECT_STATUS.req);
  effect.onError = effect.on(({ status }) => status === EFFECT_STATUS.err);

  return effect;
};

// ------------------------------------
// ------------- TESTS ----------------
// ------------------------------------

const api = {
  getUser() {
    return new Promise(r => setTimeout(r, 150, { name: 'Tom Sawyer', age: 12 }));
  },
};

describe('createNode', () => {
  it('individual subscribers by selectors', () => {});
  it('computed subscribe calls one time', async () => {
    const getUser = createEffect(api.getUser);
    // you can use `Object.assign` instead spread
    // `reset` - call when initiate
    const userData = createNode({
      firstName: {
        reset: () => '',
        ...getUser.onResponse(({ name }) => name.split(' ')[0]),
      },
      lastName: {
        reset: () => '',
        ...getUser.onResponse(({ name }) => name.split(' ')[1]),
      },
      age: {
        reset: () => NaN,
        ...getUser.onResponse(({ age }) => age),
      },
    });

    const { select } = userData.select;

    const userName = createNode({
      reset: () => '',
      [[select.firstName, select.lastName, select.age]]: ([firstName, lastName, age]) => {
        const prefix = age > 18 ? 'Mr. ' : '';
        return `${prefix}${firstName} ${lastName}`;
      },
    });

    const callback = jest.fn();

    userName.watch(callback);

    getUser();

    return new Promise(callback).then(() => new Promise(r => setTimeout(r))).then(() => {
      expect(callback.mock.calls.length).toBe(1);
      expect(userName.get()).toBe('Tom Sawyer');
    });
  });
});