test.js

import expect from 'expect';
import AppConstants from '../../../app/AppConstants';
import store from '../../store';
import { selectLastReadMessageByChannelId } from './channelSelectors';

describe('channel', () => {
  it('should store the messageId when clearing unreads', () => {
    const channelId = 1;
    const messageId = 2;
    store.dispatch({
      type: AppConstants.CHANNEL_UNREADS_CLEARED,
      payload: {
        id: channelId,
        messageId
      }
    });
    expect(selectLastReadMessageByChannelId(store.getState(), channelId)).toEqual(messageId);
  });
});

if you decided to change [x], you have to change [y]

Apps always change. For me, about the only thing I care about is that.

My favorite code allows me to change one thing w/o having to change many things.

For example, I don't assert an exact DOM structure for UI tests, I just assert that the user's name is displayed: I don't care if its in a <b/> or <span/>. You've got the same thing going on here by not coupling your tests to your state tree, you're testing "does this work" not "how does this work" and its 💯

(there are times I look at how simple my reducers--and everything else in a react redux app--are to think about and wonder why I'm even writing tests at all ...)