About

Install

For TypeScript install Jest with ts-jest preprocessor with:

npm install --save-dev jest @types/jest ts-jest

Because we are running with ts-jest create the jest.config.js file, which will inform Jest how to handle .ts files correctly.

npx ts-jest config:init

Running

Test files for Jest are named <file>.test.ts.

By specific filename

Specific filename AND path

Run only the tests that were specified with their exact paths.

npx jest --runTestsByPath [path]/[filename]

Specific filename

Find and run the tests that cover a space separated list of source files.

It will regex only by the specified name, so if multiple files have the same name it will execute all of them.

npx jest --findRelatedTests [filename]

With coverage

npx jest --coverage

On watch mode

Watch files for changes and rerun tests.

To rerun only changed files

# Runs `jest -o` by default
npx jest --watch

To rerun all files

npx jest --watchAll