Jest vs Spock comparison of testing frameworks
What are the differences between Jest and Spock?

	Jest https://jestjs.io	Spock http://spockframework.org/
Programming language	JavaScript	Java
Category	Unit Testing	Unit Testing
General info	A Unit Testing framework focused on simplicity This is a Unit test framwork especially designed for the React.JS, Babel, TypeScript, Node, React, Angular and Vue projects. It usually worked with Enzyme(Integration testing)	Spock is a testing and specification framework for Java and Groovy applications Spock has a highly expressive specification language, and due to its JUnit runner, Spock is compatible with most IDEs, build tools, and continuous integration servers.Spock is inspired from JUnit, RSpec, jMock, Mockito, Groovy, Scala, Vulcans among others
xUnit Set of frameworks originating from SUnit (Smalltalk's testing framework). They share similar structure and functionality.	No	No
Client-side Allows testing code execution on the client, such as a web browser	Yes You can easily test methods, properties, UI element actions and other front-end functionalities	Yes Spock tests front-end components and functionality by unit testing individual classes and functions
Server-side Allows testing the bahovior of a server-side code	Yes Back-end server behaviour also can be tested with Jest much in the same way as the front-end tests.	Yes Spock tests back-end components and functionality by unit testing individual classes and functions
Fixtures Allows defining a fixed, specific states of data (fixtures) that are test-local. This ensures specific environment for a single test	Yes Fixtures are supported, Jest has many helper functions such as: BeforeEach and afterEach If you have some work you need to do repeatedly for many tests, beforeAll and afterAll if you only need to do setup once, at the beginning of a file.	Yes Spock contains four methods for setting up environments :setup() (run before every feature method), cleanup() (run after every feature method), setupSpec() (run before the first feature method), cleanupSpec() (run after the last feature method)
Group fixtures Allows defining a fixed, specific states of data for a group of tests (group-fixtures). This ensures specific environment for a given group of tests.	Yes Jest supports group fixtures	Yes You can use the fixture methods to setup environments for groups of tests.
Generators Supports data generators for tests. Data generators generate input data for test. The test is then run for each input data produced in this way.	N/A	N/A
Licence Licence type governing the use and redistribution of the software	MIT License	Apache License 2.0
Mocks Mocks are objects that simulate the behavior of real objects. Using mocks allows testing some part of the code in isolation (with other parts mocked when needed)	Jest uses a custom resolver for imports in your tests making it simple to mock any object outside of your test’s scope. You can use mocked imports with the rich Mock Functions API to spy on function calls with readable test syntax.	Yes Spock has inbuilt mocking capabilities and has no need for external libraries
Grouping Allows organizing tests in groups	Yes You can declare as many test suites as you want. Grouping of tests together is done using a describe block	Yes You can create suites manually in spock
Other Other useful information about the testing framework