ts-jest

Table of Contents

• Versioning
• Usage
• Options
  • Known limitations for TS compiler options
• How to Contribute
  • Quickstart to run tests (only if you're working on this package)
• License

Versioning

From version "jest": "17.0.0" we are using same MAJOR.MINOR as Jest.
For "jest": "< 17.0.0" use "ts-jest": "0.1.13". Docs for it see here.

Usage

To use this in your project, run:

npm install --save-dev ts-jest

Modify your project's package.json so that the jest section looks something like:

{
  "jest": {
    "transform": {
      ".(ts|tsx)": "<rootDir>/node_modules/ts-jest/preprocessor.js"
    },
    "testRegex": "(/__tests__/.*|\\.(test|spec))\\.(ts|tsx|js)$",
    "moduleFileExtensions": [
      "ts",
      "tsx",
      "js"
    ]
  }
}

This setup should allow you to write Jest tests in Typescript and be able to locate errors without any additional gymnastics.

By default jest does not provide code coverage remapping for transpiled codes, so if you'd like to have code coverage it needs additional coverage remapping. This can be done via writing custom processing script, or configure testResultsProcessor to use built-in coverage remapping in ts-jest.

{
  "jest": {
    "transform": {
      ".(ts|tsx)": "<rootDir>/node_modules/ts-jest/preprocessor.js"
    },
    "testResultsProcessor": "<rootDir>/node_modules/ts-jest/coverageprocessor.js"
  }
}

Note: If you're experiencing remapping failure with source lookup, it may due to pre-created cache from jest. It can be manually deleted, or execute with --no-cache to not use those.

React Native

There is a few additional steps if you want to use it with React Native.

Install babel-jest and babel-preset-react-native modules.

npm install -D babel-jest babel-preset-react-native

Ensure .babelrc contains:

{
  "presets": ["react-native"]
}

In package.json, inside jest section, the transform should be like this:

"transform": {
  "^.+\\.js$": "<rootDir>/node_modules/babel-jest",
  ".(ts|tsx)": "<rootDir>/node_modules/ts-jest/preprocessor.js"
}

Options

By default this package will try to locate tsconfig.json and use its compiler options for your .ts and .tsx files.
But you are able to override this behaviour and provide another path to your config for TypeScript by using __TS_CONFIG__ option in globals for jest:

{
  "jest": {
    "globals": {
      "__TS_CONFIG__": "my-tsconfig.json"
    }
  }
}

Or even declare options for tsc instead of using separate config, like this:

{
  "jest": {
    "globals": {
      "__TS_CONFIG__": {
        "module": "commonjs",
        "jsx": "react"
      }
    }
  }
}

For all available options see TypeScript docs.

Known limitations for TS compiler options

• You can't use "target": "ES6" while using node v4 in your test environment;
• You can't use "react": "preserve" for now (see progress of this issue);
• If you use "baseUrl": "<path_to_your_sources>", you also have to change jest config a little bit:

"jest": {
  "moduleDirectories": ["node_modules", "<path_to_your_sources>"]
}

How to Contribute

If you have any suggestions/pull requests to turn this into a useful package, just open an issue and I'll be happy to work with you to improve this.

Quickstart to run tests (only if you're working on this package)

git clone https://github.com/kulshekhar/ts-jest
cd ts-jest
npm install
npm test

License

Copyright (c) Authors.
This source code is licensed under the MIT license.