Simple redux test pattern

reducerTestSkeleton.js

/* 
 * ReducerTestSkeleton
 * Author: Will Farley <@goldhand>
 * Skeleton for writing simple reducer tests.
 * takes a reducer and expects it to return stateAfter when invoked with stateBefore and action.
 * 
 */
// Example: =
// const dummyTest = () => reducerTestSkeleton(
//   {counter: 1},
//   {counter: 2},
//   {type: 'INCREASE'},
//   dummyReducer 
//   );
// describe('Dummy Reducer Tests', function() {
//   it('1 + 1 = 2', function() {
//     dummyTest();
//   });
// };
import expect from 'expect';
import deepFreeze from 'deep-freeze';


const reducerTestSkeleton = (
  stateBefore,
  stateAfter,
  action,
  reducer,
) => {
  deepFreeze(stateAfter);
  deepFreeze(action);

  expect(reducer(stateBefore, action)
  ).toEqual(stateAfter);
};

export default reducerTestSkeleton;

reduxDummyTest.js

import expect from 'expect';
import deepFreeze from 'deep-freeze';


const dummyReducer = (state, action) => {
  switch (action.type) {
    case 'INCREASE':
      return {
        counter: state.counter + 1,
      };
    case 'DECREASE':
      return {
        counter: state.counter - 1,
      };
    default:
      return state;
  }
};

const dummyTestIncrease = (successMsg) => {
  const stateBefore = {
    counter: 1,
  };
  const stateAfter = {
    counter: 2,
  };
  const action = {
    type: 'INCREASE',
  };
  deepFreeze(stateBefore);
  deepFreeze(action);

  expect(
    dummyReducer(stateBefore, action)
  ).toEqual(stateAfter);

  console.info(successMsg);
};

const dummyTestDecrease = (successMsg) => {
  const stateBefore = {
    counter: 2,
  };
  const stateAfter = {
    counter: 1,
  };
  const action = {
    type: 'DECREASE',
  };
  deepFreeze(stateBefore);
  deepFreeze(action);

  expect(
    dummyReducer(stateBefore, action)
  ).toEqual(stateAfter);

  console.info(successMsg);
};


const runTests = (successMsg) => {
  dummyTestIncrease('increase test passed');
  dummyTestDecrease('decrease test passed');

  console.info(successMsg);
};

runTests('all tests passed');

reduxMochaDummyTest.js

/*
 * Same tests as before this time using the mocha testing suite
 */

import expect from 'expect';
import deepFreeze from 'deep-freeze';


const dummyReducer = (state, action) => {
  switch (action.type) {
    case 'INCREASE':
      return {
        counter: state.counter + 1,
      };
    case 'DECREASE':
      return {
        counter: state.counter - 1,
      };
    default:
      return state;
  }
};

const dummyTestIncrease = () => {
  const stateBefore = {
    counter: 1,
  };
  const stateAfter = {
    counter: 2,
  };
  const action = {
    type: 'INCREASE',
  };
  deepFreeze(stateBefore);
  deepFreeze(action);

  expect(
    dummyReducer(stateBefore, action)
  ).toEqual(stateAfter);
};

const dummyTestDecrease = () => {
  const stateBefore = {
    counter: 2,
  };
  const stateAfter = {
    counter: 1,
  };
  const action = {
    type: 'DECREASE',
  };
  deepFreeze(stateBefore);
  deepFreeze(action);

  expect(
    dummyReducer(stateBefore, action)
  ).toEqual(stateAfter);
};

// describe and it are global functions from mocha
describe('Dummy Reducer Tests', function() {
  it('1 + 1 = 2', function() {
    dummyTestIncrease();
  });
  it('2 - 1 = 1', function() {
    dummyTestDecrease();
  });
});