What is a goal:
We want to have component tests for React in the same maner as selenium tests.

What's is included in this PR:

1. Support for mocha features compilers and require. This should solve these issues: Coffeescript support #474 [ Question ] How to get babel working to support imports? #370
2. Add option --transpile. When it's true, then transpiled code will process without issues. And also React components will displays correctly in test stdout.
3. Add Enzyme helper. Currently only mount methods. Have to add some manipulation methods

How to run it:

1. add these deps to package.json:
   enzyme
   enzyme-adapter-react-16
   jsdom
   react-element-to-string
   sinon
   babel-polyfill
   babel-core
   esprima
   escodegen

and install them.

2. create .babelrc file to store babel settings. If you are using webpack aliases in your project you also have to install babel-plugin-webpack-aliases:
   e.g.

{
  "presets": [ "react", "es2015", "stage-1" ],
  "plugins": [
    [ "babel-plugin-webpack-aliases", { "config": "./webpack.config.js" } ]
  ]
}

3. Write a test. E.g.:

import React from 'react';
import Button from '_shared/components/button';

Feature('test');

Scenario('simple test', async (I) => {
  const component = await I.mountComponent(<Button/>);
  console.log(component.html());
});

4. create run script in package.json. E.g.: codeceptjs run --transpile --compilers js:babel-core/register,js:babel-polyfill

5. In my case there are some css styles imports in project. They can't be traspiled by babel automaticly. In our project it's webpack job, so we have to emulate this imports. To do this I create a special js file:

// ./tests/helper.js
function donothing() {
  return null;
}

require.extensions['.css'] = donothing;
require.extensions['.less'] = donothing;
require.extensions['.scss'] = donothing;
require.extensions['.styl'] = donothing;

and add it to codeceptjs run script:
codeceptjs run -R mocha-multi --transpile --compilers js:babel-core/register,js:babel-polyfill,css:./tests/helper

So next steps for this:

• Test it with real project
• Add more Enzyme and sinon methods
• Write tests for these feature
• Create a boilerplate project for enzyme