Note: Looking for collaborators. Want to help improve ts-jest?
ts-jest
is a TypeScript preprocessor with source map support for Jest that lets you use Jest to test projects written in TypeScript.
- Usage
- Default Setup
- Configuration
- Use cases
- Angular 2
- Tips
- Known Limitations
- How to Contribute
- License
To use this in your project, run:
npm install --save-dev ts-jest @types/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.
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.
Prior to version 20.0.0
, coverage reports could be obtained using the inbuilt coverage processor in ts-jest
. Starting with version 20.0.0
, ts-jest
delegates coverage processing to jest and no longer includes a coverage processor.
To generate coverage results, set the mapCoverage
property in the jest
configuration section to true
.
Please note that the
outDir
property in thejest
configuration section is removed in coverage mode, due to #201.
ts-jest
tries to ship with sensible defaults, to get you on your feet as quickly as possible.
Sourcemaps should work out of the box. That means your stack traces should have the correct line numbers, and you should be able to step through the TypeScript code using a debugger.
ts-jest
automatically located your tsconfig
file.
If you want to compile typescript with a special configuration, you can do that too
If you're on a codebase where you're using synthetic default imports, e.g.
//Regular imports
import * as React from 'react';
//Synthetic default imports:
import React from 'react';
ts-jest
tries to support that. If allowSyntheticDefaultImports
is set to true in your tsconfig
file, it uses babel
to automatically create the synthetic default exports for you - nothing else needed.
You can opt-out of this behaviour with the skipBabel flag
Just like Jest ts-jest
automatically uses babel to hoist your jest.mock()
calls to the top of your file.
You can opt-out of this behaviour with the skipBabel flag
If the default setup doesn't address your requirements, you can create a custom setup to suit your project.
By default this package will try to locate tsconfig.json
and use its compiler options for your .ts
and .tsx
files.
You can override this behaviour by pointing ts-jest to a custom TypeScript configuration file.
You can do this by setting the tsConfigFile
option in your global variables under the ts-jest
key to path of the
custom configuration file (relative to the project's root directory)
{
"jest": {
"globals": {
"ts-jest": {
"tsConfigFile": "my-tsconfig.json"
}
}
}
}
Warning: Using __TS_CONFIG__ option in globals is deprecated and soon will be removed.
For all available tsc
options see TypeScript docs.
Note that if you haven't explicitly set the module
property through a separate configuration file with tsConfigFile
, it will be overwritten to commonjs
(regardless of the value in tsconfig.json
) since that is the format Jest expects. This only happens during testing.
If you don't use mocks, or synthetic default imports you can skip the babel-transpilation step.
This means jest.mock()
calls will not be hoisted to the top,
and synthetic default exports will never be created.
Simply add skipBabel to your global variables under the ts-jest
key:
//This will skip babel transpilation
{
"jest": {
"globals": {
"ts-jest": {
"skipBabel": true
}
}
}
}
When using Babel, ts-jest, by default, doesn't use the .babelrc
file. If you want ts-jest to use .babelrc
, you should set the globals > ts-jest > useBabelrc
flag to true
in your jest
configuration.
{
"jest": {
"globals": {
"ts-jest": {
"useBabelrc": true
}
}
}
}
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"],
"sourceMaps": "inline"
}
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"
}
Fully completed jest section should look like this:
"jest": {
"preset": "react-native",
"transform": {
"^.+\\.js$": "<rootDir>/node_modules/babel-jest",
".(ts|tsx)": "<rootDir>/node_modules/ts-jest/preprocessor.js"
},
"testRegex": "(/__tests__/.*|\\.(test|spec))\\.(ts|tsx|js)$",
"moduleFileExtensions": [
"ts",
"tsx",
"js"
]
}
If only testing typescript files then remove the js
option in the testRegex.
When using Jest with Angular (a.k.a Angular 2) apps you will likely need to parse HTML templates. If you're unable to add html-loader
to webpack config (e.g. because you don't want to eject from angular-cli
) you can do so by defining __TRANSFORM_HTML__
key in globals
for jest
.
{
"jest": {
"globals": {
"__TRANSFORM_HTML__": true
}
}
}
You'll also need to extend your transform
regex with html
extension:
{
"jest": {
"transform": {
"^.+\\.(ts|tsx|js|html)$": "<rootDir>/node_modules/ts-jest/preprocessor.js"
}
}
}
If you have dependencies on npm packages that are written in TypeScript but are
not published in ES5 you have to tweak your configuration. For example
you depend on a private scoped package @foo/bar
you have to add following to
your Jest configuration:
{
// ...
"transformIgnorePatterns": [
"<rootDir>/node_modules/(?!@foo)"
]
// ...
}
By default Jest ignores everything in node_modules
. This setting prevents Jest from ignoring the package you're interested in, in this case @foo
, while continuing to ignore everything else in node_modules
.
- You can't use
"target": "ES6"
while usingnode v4
in your test environment; - You can't use
"jsx": "preserve"
for now (see progress of this issue); - If you use
"baseUrl": "<path_to_your_sources>"
, you also have to changejest config
a little bit:
"jest": {
"moduleDirectories": ["node_modules", "<path_to_your_sources>"]
}
- ts-jest only returns syntax errors from tsc
- Non syntactic errors do not show up in jest
- If you only want to run jest if tsc does not output any errors, a workaround is
tsc --noEmit -p . && jest
If the jest.mock()
calls is placed after actual code, (e.g. after functions or classes) and skipBabel
is not set,
the line numbers in stacktraces will be off.
We suggest placing the jest.mock()
calls after the imports, but before any actual code.
Breakpoints currently work in WebStorm, but not Visual Studio Code. debugger
; statements work in both, and will
map the TypeScript code correctly to the transpiled Javascript.
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.
git clone https://github.com/kulshekhar/ts-jest
cd ts-jest
npm install
npm test
Note: If you are cloning on Windows, you may have to run git config --system core.longpaths true
for Windows to stop complaining about long filenames.
Copyright (c) Authors. This source code is licensed under the MIT license.