This module attempts to address issues I found when trying to use typescript-require to test TypeScript code with Mocha.
My first thought was to use the TypeScript Compiler API to directly trigger compilation. I thought this would be cleaner than trying to run a script that runs the command line compiler.
This effort was simulataneously a success and a failure.
It was a success because I learned a bit about the TypeScript Compiler
API and managed to write a compiler plugin for Mocha that actually
works. I also consider it a success because it triggers the
compilation using the options specified by a tsconfig.json which
means the results of running the tests through mocha should be the
same as the results you would get if you invoked tsc and then
mocha serially.
It was a failure because my main goal was to leverage the --watch
functionality in Mocha and that still doesn't work (more on that in a
second). I recognized that while I could use a build tool like gulp
or grunt to build the TypeScript code and then run mocha on it, I
thought it would be much more elegant if mocha "just worked".
The reason the watch functionality doesn't work is that when tsc
compiles the tests it depends on lots of code, not just the TypeScript
code that mocha sees. So if you change the actual test code, this
works just fine. But if you change code that the tests leverage
(i.e., the code you are trying to test), it doesn't notice the
changes.
In addition to the limitation of not detecting changes in the code to be tested (documented above) while in watch mode, there is another limitation of this module. It uses the compiler API for TypeScript v1.8.0+ (which isn't even officially released as of now).
I'd be happy to have others contributing to this in the hope that it can eventually achieve the goals I set out to accomplish. But for now, I'm just making it available so people can leverage the limited functionality it provides.