Introduction to jest-watch-typeahead

The jest-watch-typeahead is a plugin for Jest, a delightful JavaScript Testing Framework with a focus on simplicity. This plugin enhances Jest’s watch mode, providing a fast and efficient way to filter and select specific tests to run. It significantly improves the developer experience when working with large test suites.

Getting Started

To begin using jest-watch-typeahead, install it via npm:

  npm install --save-dev jest-watch-typeahead

Once installed, add the plugin to your Jest configuration:

  
  // jest.config.js
  module.exports = {
    watchPlugins: [
      'jest-watch-typeahead/filename',
      'jest-watch-typeahead/testname'
    ],
  };
  

Core Features and API Examples

1. Filename Plugin

Filter your tests by filename:

  
  jest --watch
  # type 'p' to filter by filename
  

2. Test Name Plugin

Filter your tests by test name patterns:

  
  jest --watch
  # type 't' to filter by test name
  

3. Example Application

Assume you have a simple application with two test files: sum.test.js and multiply.test.js.

  
  // sum.test.js
  test('adds 1 + 2 to equal 3', () => {
    expect(1 + 2).toBe(3);
  });

  // multiply.test.js
  test('multiplies 2 * 3 to equal 6', () => {
    expect(2 * 3).toBe(6);
  });
  

Run jest –watch and use the filename and test name typeahead plugins to filter your tests quickly.

Additional Options

There are several additional configuration options you can explore:

  
  module.exports = {
    watchPlugins: [
      ['jest-watch-typeahead/filename', { key: 'f' }],
      ['jest-watch-typeahead/testname', { key: 'n' }],
    ],
  };
  

These options allow you to customize the keys used to trigger the typeahead modes.

Conclusion

The jest-watch-typeahead plugin is an invaluable tool for developers working with large test suites. It improves the efficiency and pleasure of running tests in watch mode. Incorporating this plugin into your development workflow will ensure a smoother and more productive testing experience.

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