npm test — --coverage never exits

问题

I am using create-react-app to create a react application. When I executes npm test -- --coverage the test never exists. npm test actually runs react-scripts test. Any Idea?

回答1:

-- --coverage part won't work, and should use one of the commands below to set CI to true.

By default npm test runs the watcher with interactive CLI. However, you can force it to run tests once and finish the process by setting an environment variable called CI.

source: React docs

Windows (cmd.exe)

• set CI=true && npm test

• set CI=true && npm run build

Windows (Powershell)

• ($env:CI = "true") -and (npm test)

• ($env:CI = "true") -and (npm run build)

Linux, macOS (Bash)

• CI=true npm test

• CI=true npm run build

---

NOT included in the docs

For Docker (node and react):

docker run -e CI=true [myImage] npm run test

回答2:

Coverage won't work with Jest in watch mode.

Because "react-scripts test --env=jsdom" works in watch mode by default, the watch mode has to be switched off while generating the coverage output.

The following excerpt from the package.json contains a line "coverage" for illustration, how code coverage can be achieved within an app which was bootet by create-react-app.

It's just the modified "test" script, where the options --watchAll=false and --coverage are added in combination:

 "scripts": {
    "start": "react-scripts start",
    "build": "react-scripts build",
    "test": "react-scripts test --env=jsdom",
    "coverage": "react-scripts test --env=jsdom --watchAll=false --coverage",
    "eject": "react-scripts eject"
  }

Please note that it is obsolete to use standalone double-dash -- .

来源：https://stackoverflow.com/questions/55991641/npm-test-coverage-never-exits