How to run Mocha tests written in TypeScript?

Issue

Setup: I have a Node project (pure Node, no browser bits) written in TypeScript. I can use the TypeScript compiler (tsc) from the typescript module to compile the code. So far so good.

However, I want to write tests using Mocha, and that's where I'm having trouble. I tried --compilers ts:typescript, but I keep getting errors like:

error TS5023: Unknown compiler option 'compilers'.

It looks like the command line to mocha ends up being passed to tsc, which is obviously not good.

Solution

For anybody who has tried and had problems with typescript-require you may want to try ts-node.

$ npm install -g ts-node
$ mocha --require ts-node/register src/**/*.spec.ts

It also appears that there has been some ongoing discussion about deprecating typescript-require in favor of ts-node.

Answered By - jpierson