jest-runtime

What is jest-runtime?

The jest-runtime package is part of the Jest testing platform. It is responsible for executing tests and their associated code within a controlled environment. It handles the evaluation of the test files, mocking of modules, and provides utilities for loading and running the tests.

What are jest-runtime's main functionalities?

Module Mocking

Allows you to mock modules to isolate your tests from their dependencies, providing a way to test modules in isolation.

jest.mock('moduleName');

Test Environment Setup

Enables you to programmatically create a test environment, including the haste map (module map) and the test runner, which can be used to execute test files.

const runtime = require('jest-runtime');
// Create a runtime to execute the test
runtime.createHasteMap(config).then(hasteMap => {
  const environment = new runtime.TestEnvironment(config);
  const runner = new runtime.TestRunner(environment, hasteMap.resolver);
  // Execute the test file
  runner.runTest(filePath);
});

Script Transformation

Provides the ability to transform scripts using Jest's built-in transformers or custom ones. This is useful for preprocessing files before they are executed in the test environment.

const runtime = require('jest-runtime');
// Create a new runtime instance
const jestRuntime = new runtime.ScriptTransformer(config);
// Transform a script
const transformedCode = jestRuntime.transformSource(filePath, fileContent, false);

Other packages similar to jest-runtime

mocha

Mocha is a feature-rich JavaScript test framework running on Node.js and in the browser, making asynchronous testing simple. It is similar to jest-runtime in that it provides a test environment and runner, but it does not include a built-in mocking library or script transformation capabilities.

jasmine

Jasmine is a behavior-driven development framework for testing JavaScript code. It does not require a DOM, and it has a clean, obvious syntax so that you can easily write tests. It is similar to jest-runtime in providing an environment for running tests, but it has a different assertion library and does not handle module mocking and script transformation in the same way.

ava

AVA is a test runner for Node.js with a concise API, detailed error output, and process isolation that lets you develop with confidence. AVA is similar to jest-runtime in that it can run tests in parallel and supports the latest JavaScript features, but it differs in its approach to mocking and does not provide a built-in mechanism for script transformation.

README

The README file is missing

Changelog

jest 16.0.0

• Previously failed tests are now always run first.
• A new concurrent reporter shows currently running tests, a test summary, a progress bar and estimated remaining time if possible.
• Improved CLI colors.
• jest <pattern> is now case-insensitive.
• Added it.only, it.skip, test.only, test.skip and xtest.
• Added --testNamePattern=pattern or -t <pattern> to run individual tests in test files.
• Jest now warns for duplicate mock files.
• Pressing a, o, p, q or enter while tests are running in the watch mode, the test run will be interrupted.
• --bail now works together with --watch.
• Added test.concurrent for concurrent async tests.
• Jest now automatically considers files and tests with the .jsx extension.
• Added jest.clearAllMocks to clear all mocks manually.
• Rewrote Jest's snapshot implementation. jest-snapshot can now be more easily integrated into other test runners and used in other projects.
• This requires most snapshots to be updated when upgrading Jest.
• Objects and Arrays in snapshots are now printed with a trailing comma.
• Function names are not printed in snapshots any longer to reduce issues with code coverage instrumentation and different Node versions.
• Snapshots are now sorted using natural sort order.
• Snapshots are not marked as obsolete any longer when using fit or when an error is thrown in a test.
• Finished migration of Jasmine matchers to the new Jest matchers.
• Pretty print toHaveBeenLastCalledWith, toHaveBeenCalledWith, lastCalledWith and toBeCalledWith failure messages.
• Added toBeInstanceOf matcher.
• Added toContainEqual matcher.
• Added toThrowErrorMatchingSnapshot matcher.
• Improved moduleNameMapper resolution.
• Module registry fixes.
• Fixed invocation of the setupTestFrameworkScriptFile script to make it easier to use chai together with Jest.
• Removed react-native special case in Jest's configuration.
• Added --findRelatedTests <fileA> <fileB> cli option to run tests related to the specified files.
• Added jest.deepUnmock to babel-plugin-jest-hoist.
• Added jest.runTimersToTime which is useful together with fake timers.
• Improved automated mocks for ES modules compiled with babel.