Testing with React's Jest and Enzyme when simulated clicks call a function that calls a promise

• React v15.1.0
• Jest v12.1.1
• Enzyme v2.3.0

I'm trying to figure out how to test a component that calls a promise in a function invoked by a click. I was expecting Jest's runAllTicks() function to help me out here, but it doesn't seem to be executing the promise.

Component:

import React from 'react';
import Promise from 'bluebird';

function doSomethingWithAPromise() {
  return new Promise((resolve) => {
    setTimeout(() => {
      resolve();
    }, 50);
  });
}

export default class AsyncTest extends React.Component {
  constructor(props) {
    super(props);

    this.state = {
      promiseText: '',
      timeoutText: ''
    };

    this.setTextWithPromise = this.setTextWithPromise.bind(this);
    this.setTextWithTimeout = this.setTextWithTimeout.bind(this);
  }

  setTextWithPromise() {
    return doSomethingWithAPromise()
      .then(() => {
        this.setState({ promiseText: 'there is text!' });
      });
  }

  setTextWithTimeout() {
    setTimeout(() => {
      this.setState({ timeoutText: 'there is text!' });
    }, 50);
  }

  render() {
    return (
      <div>
        <div id="promiseText">{this.state.promiseText}</div>
        <button id="promiseBtn" onClick={this.setTextWithPromise}>Promise</button>
        <div id="timeoutText">{this.state.timeoutText}</div>
        <button id="timeoutBtn" onClick={this.setTextWithTimeout}>Timeout</button>
      </div>
    );
  }
}

And the tests:

import AsyncTest from '../async';
import { shallow } from 'enzyme';
import React from 'react';

jest.unmock('../async');

describe('async-test.js', () => {
  let wrapper;

  beforeEach(() => {
    wrapper = shallow(<AsyncTest />);
  });

  // FAIL
  it('displays the promise text after click of the button', () => {
    wrapper.find('#promiseBtn').simulate('click');

    jest.runAllTicks();
    jest.runAllTimers();

    wrapper.update();

    expect(wrapper.find('#promiseText').text()).toEqual('there is text!');
  });

  // PASS
  it('displays the timeout text after click of the button', () => {
    wrapper.find('#timeoutBtn').simulate('click');

    jest.runAllTimers();

    wrapper.update();

    expect(wrapper.find('#timeoutText').text()).toEqual('there is text!');
  });
});

There isn't much around needing to somehow wait for the promise to fulfill before ending the test. There are two main ways of doing it from your code that I can see.

1. independently test that onClick and your promise methods. So check that onClick calls the correct function, but spying on setTextWithPromise, triggering a click and asserting that setTextWithPromise was called. Then you can also get the component instance and call that method which returns the promise you can attach a handler and assert it did the right thing.

2. expose a callback prop that you can pass in that is called when the promise resolves.