Add Mocha Test cases

[sayedihashimi]

We should add mocha test cases like [generator-aspnet](https://github.com/OmniSharp/generator-aspnet) has.

When @spboyer implemented the test cases initially he found a bunch of issues. I think we should get this project started off on the right foot and have the test cases in place so that users don't run into the issues that @spboyer found while implementing the mocha test cases.

@SamuelEnglard you can take a look at the existing generator-aspnet test cases, and if have questions please reach out to @spboyer.