Promise flow utilities for tahini testing

testing-util.js

// this does our redux flow backwardsification for us
// subscribe -> resolve next state; run trigger function

export const getNextState = (store, fn = ()=>0) => (...args)=> (
  new Promise((s, j)=>{
    const f = store.subscribe(()=>{
      f();
      s(store.getState());
    });

    fn(...args);
  }) );

// saves us a few functional programming points
export const toJS = state => state.toJS();

// turns expectation errors into rejected promises for jest to report
// fn here will be our expectation block
export const rejectify = fn => state => {
  try{
    fn(state);
    return Promise.resolve();
  } catch(e) {
    return Promise.reject(e);
  }
};