Paths mapping

If you use "baseUrl" and "paths" options in your tsconfig file, you should make sure the "moduleNameMapper" option in your Jest config is setup accordingly.

ts-jest provides a helper to transform the mapping from tsconfig to Jest config format, but it needs the .js version of the config file.

Example

TypeScript config

With the below config in your tsconfig:

// tsconfig.json
{
  "compilerOptions": {
    "baseUrl": ".",
    "paths": {
      "@App/*": ["src/*"],
      "lib/*": ["common/*"]
    }
  }
}

Jest config (without helper)

// jest.config.js
module.exports = {
  // [...]
  moduleNameMapper: {
    '^@App/(.*)$': '<rootDir>/src/$1',
    '^lib/(.*)$': '<rootDir>/common/$1',
  },
}

// package.json
{
  // [...]
  "jest": {
    "moduleNameMapper": {
      "^@App/(.*)$": "<rootDir>/src/$1",
      "^lib/(.*)$": "<rootDir>/common/$1"
    }
  }
}

Jest config (with helper)

// jest.config.js
const { pathsToModuleNameMapper } = require('ts-jest/utils')
// In the following statement, replace `./tsconfig` with the path to your `tsconfig` file
// which contains the path mapping (ie the `compilerOptions.paths` option):
const { compilerOptions } = require('./tsconfig')

module.exports = {
  // [...]
  roots: ['<rootDir>'],
  modulePaths: [compilerOptions.baseUrl], // <-- This will be set to 'baseUrl' value
  moduleNameMapper: pathsToModuleNameMapper(compilerOptions.paths /*, { prefix: '<rootDir>/' } */),
}