Jest · Just ___

Jest is one of the most popular testing libraries in the Javascript ecosystem. It is also a preset supported out of the box inside the just-task-preset library. Similar to the other presets, this task function assumes that you have a jest.config.js at the root of the project.

// just-task.js
import { jestTask } from 'just-task-preset';
task('test', jestTask());

You can pass in a few options like any another preset tasks in the just-task-preset library.

// just-task.js
import { jestTask } from 'just-task-preset';

const options = {
  runInBand: true
};

task('test', jestTask(options));

Available Options

config

You can pass in a different jest.config.js file to the jestTask().

runInBand

This causes the jest runner to run the tests in a single thread.

coverage

This causes jest to collect coverage information. It is much slower, and therefore is turned OFF by default.

updateSnapshots

This causes the jestTask() to update snapshots. Configuration of the snapshot location is subject to the jest.config.js file.

Next Steps

Learn about the tslint preset