Configure Jest Global Tests Setup With .ts File (TypeScript)

Answer :

I found a solution.

My initial project structure was:

.
|--src
|  |--service.ts
|--tests
|  |--service.test.ts
|--dist
|--tsconfig.json 
|--package.json

Jest configuration in package.json:

"jest": {
  "globals": {
    "ts-jest": {
      "tsConfigFile": "tsconfig.json"
    }
  },
  "moduleFileExtensions": ["ts","js"],
  "transform": {
    "^.+\\.(ts|tsx)$": "./node_modules/ts-jest/preprocessor.js"
  },
  "testMatch": [
    "**/tests/**/*.test.(ts|js)"
  ],
  "testEnvironment": "node"
}

With this configuration ts-jest perform in memory transpiling of the .ts files.
I have outDir option in compilerOptions of my tsconfig.json, but nothing is written in that outDir and because I cann't use transpiled jest-config.js

Then I move tests folder in src and change Jest config.
New structure of the project is:

.
|--src
|  |--service.ts
|  |--tests
|     |--service.test.ts
|     |--jest-config.ts
|--dist
|--tsconfig.json 
|--package.json

New Jest config is:

"jest": {
  "globalSetup": "./dist/tests/jest-config.js",
  "moduleFileExtensions": ["ts", "js", "json"],
  "testMatch": [
    "**/dist/**/*.test.js"
  ],
  "testEnvironment": "node"
}

Now I can use jest-config.js for global setup in Jest.

Addition

• Jest setup file (in my example jest-config.js) must export one async function:

  
  
  

  module.exports = async function() { ... }




• Before running the tests, you need to compile source .ts files.