How to setup Karma/Jasmine with Typescript support for a NestJs project

I’m submitting a…

[ ] Regression 
[ ] Bug report
[ ] Feature request
[ x ] Documentation issue or request
[ ] Support request => Please do not submit support request here, instead post your question on Stack Overflow.

Current behavior

The testing documentation is great but there’s no setup part and and the starters probably don’t want to enforce any testing framework, we have to do that setup ourselves, which is pretty hard for angular-cli user 😅 (focus on writing code, not setting things up)

A bit of help would be veeeeery welcome for that and I’m guessing that I’m not the only one who want that kind of setup so maybe there should be some section in doc how to make a basic setup for testing a Nest project (at least with Typescript support).

So I’m creating a starter NestJs for the back, Angular for the front: https://github.com/maxime1992/nest-angular-starter

I used karma-typescript and made a setup. It ended up with some errors related to my karma conf, which has now been solved.

The only last error is directly related to Nest and/or Express I think. When I launch the tests I end up with:

{ "message": "An error was thrown in afterAll\nUncaught TypeError: Object prototype may only be an Object or null: undefined", "str": "An error was thrown in afterAll\nUncaught TypeError: Object prototype may only be an Object or null: undefined" }

And I can also have this more complete stacktrace:

Chromium 64.0.3282 (Ubuntu 0.0.0) ERROR { "message": "Uncaught TypeError: Object prototype may only be an Object or null: undefined\nat /tmp/karma-typescript-bundle-26778Zp2MqPkTFGxe.js:57170:18\n\nTypeError: Object prototype may only be an Object or null: undefined\n at Function.create (<anonymous>)\n at Object.global.wrappers./home/maxime/Documents/nest-angular-starter/node_modules/express/lib/request.js.depd (/tmp/karma-typescript-bundle-26778Zp2MqPkTFGxe.js:57170:18)\n at require (/home/maxime/Documents/nest-angular-starter/node_modules/karma-typescript/src/client/commonjs.js:17:25)\n at /home/maxime/Documents/nest-angular-starter/node_modules/karma-typescript/src/client/commonjs.js:18:24\n at Object.global.wrappers./home/maxime/Documents/nest-angular-starter/node_modules/express/lib/express.js.body-parser (/tmp/karma-typescript-bundle-26778Zp2MqPkTFGxe.js:57683:11)\n at require (/home/maxime/Documents/nest-angular-starter/node_modules/karma-typescript/src/client/commonjs.js:17:25)\n at /home/maxime/Documents/nest-angular-starter/node_modules/karma-typescript/src/client/commonjs.js:18:24\n at Object.global.wrappers./home/maxime/Documents/nest-angular-starter/node_modules/express/index.js../lib/express (/tmp/karma-typescript-bundle-26778Zp2MqPkTFGxe.js:57787:18)\n at require (/home/maxime/Documents/nest-angular-starter/node_modules/karma-typescript/src/client/commonjs.js:17:25)\n at /home/maxime/Documents/nest-angular-starter/node_modules/karma-typescript/src/client/commonjs.js:18:24", "str": "Uncaught TypeError: Object prototype may only be an Object or null: undefined\nat /tmp/karma-typescript-bundle-26778Zp2MqPkTFGxe.js:57170:18\n\nTypeError: Object prototype may only be an Object or null: undefined\n at Function.create (<anonymous>)\n at Object.global.wrappers./home/maxime/Documents/nest-angular-starter/node_modules/express/lib/request.js.depd (/tmp/karma-typescript-bundle-26778Zp2MqPkTFGxe.js:57170:18)\n at require (/home/maxime/Documents/nest-angular-starter/node_modules/karma-typescript/src/client/commonjs.js:17:25)\n at /home/maxime/Documents/nest-angular-starter/node_modules/karma-typescript/src/client/commonjs.js:18:24\n at Object.global.wrappers./home/maxime/Documents/nest-angular-starter/node_modules/express/lib/express.js.body-parser (/tmp/karma-typescript-bundle-26778Zp2MqPkTFGxe.js:57683:11)\n at require (/home/maxime/Documents/nest-angular-starter/node_modules/karma-typescript/src/client/commonjs.js:17:25)\n at /home/maxime/Documents/nest-angular-starter/node_modules/karma-typescript/src/client/commonjs.js:18:24\n at Object.global.wrappers./home/maxime/Documents/nest-angular-starter/node_modules/express/index.js../lib/express (/tmp/karma-typescript-bundle-26778Zp2MqPkTFGxe.js:57787:18)\n at require (/home/maxime/Documents/nest-angular-starter/node_modules/karma-typescript/src/client/commonjs.js:17:25)\n at /home/maxime/Documents/nest-angular-starter/node_modules/karma-typescript/src/client/commonjs.js:18:24" }

Expected behavior

I’d just love to be able to kickstart a Nest app and focus on code/tests. If anybody could help me make that works, then maybe we could also start a dedicated documentation section for that kind of setup?

Minimal reproduction of the problem with instructions

You can find more information where I started this issue here: https://github.com/monounity/karma-typescript/issues/32#issuecomment-370177855

I also have a repo where you can try it on your own:

git clone https://github.com/maxime1992/nest-angular-starter.git
git checkout feat/init-repo
yarn
yarn run back:test

What is the motivation / use case for changing the behavior?

Focus on code/tests, not tooling

Environment

Nest version: 4.6.5
 
For Tooling issues:
- Node version: 8.2
- Platform:  Ubuntu

[CoreyCole]

I actually like this solution more:

• remove exclude **/*.spec.ts from tsconfig.json
• add this is tsconfig.json after compilerOptions

"typeAcquisition": {
    "include": [
      "jest"
    ]
  }

[psaunders]

I agree there is a missing step in the testing documentation, if you following along with the docs doing the Cats examples you will get an error saying “cannot find name ‘describe’” on the tests. It’d be really great if the demo project had a basic test in it so that the package.json file is in a good state.