Allow resetting the state of the Encore singleton

[stof]

Closes #48

[stof]

AFAIK, we have no tests for the Encore layer itself currently (which might be related to the fact that it was not resettable btw), which is why there is no test changes currently.

[weaverryan]

AFAIK, we have no tests for the Encore layer itself currently

Correct: specifically there is no test for index.js. I think it would be a good idea to create a smoke test - e.g. configure Encore with a few basic things, call getWebpackConfig(), reset it, configure a few other things and call getWebpackConfig() again (asserting very basic things on the config in both cases). If you can add that here, awesome. Otherwise, we can add it later - this is a pretty simple patch and doesn't affect any existing code.

[stof]

getWebpackConfig is hard to test cleanly if you want to cover it all, as it calls process.exit. This would require actually using a subprocess. So I will leave it for later

[weaverryan]

It only calls process.exit() if there is a validation error. So yea, testing that case is not worth it. But testing a successful case as a "smoke test" should not be too hard.

[weaverryan]

Thanks Stof!