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

	Spock http://spockframework.org/	Mocha https://mochajs.org
Programming language	Java	JavaScript
Category	Unit Testing	Unit Testing, Intergration Testing, End-to-End Testing
General info	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	Mocha is a widely used JavaScript test framework for Node.js Mocha is a simple, flexible and the one of the widely adopted JS test framework. Mocha usually runs tests serially which enables the accurate reporting. Also it's useful for asynchronous testing, and provides various king of test reports. Spec is default test reporter for mocha, there are many test reports like Nyan, Dot matrix, Tap, Landing strip, List and Progress. Mocha is being used with many other test frameworks like Selenium WebDriver, Webdriver.io, wd and Cypress
xUnit Set of frameworks originating from SUnit (Smalltalk's testing framework). They share similar structure and functionality.	No	Yes It has an XUnit reporter available which outputs an XUnit-compatible XML document, often applicable in CI servers.
Client-side Allows testing code execution on the client, such as a web browser	Yes Spock tests front-end components and functionality by unit testing individual classes and functions	Yes Mocha Runs in the browser and is used widely to test front-end components and functionality. It can test various DOM elements, front-end functions and so on.
Server-side Allows testing the bahovior of a server-side code	Yes Spock tests back-end components and functionality by unit testing individual classes and functions	Yes Mocha provides convenient ways of testing the Node server.It works well with Chai (an assertion library) where it provides the environment for writing server-side tests while we write the tests with Chai
Fixtures Allows defining a fixed, specific states of data (fixtures) that are test-local. This ensures specific environment for a single test	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)	Mocha provides the hooks before(), after(), beforeEach(), and afterEach() to set up preconditions and clean up after your tests
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 You can use the fixture methods to setup environments for groups of tests.	N/A Mocha allows grouping of fixtures
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
Licence Licence type governing the use and redistribution of the software	Apache License 2.0	MIT License
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)	Yes Spock has inbuilt mocking capabilities and has no need for external libraries	Provides Mocking capabilities through third party libraries like sinon.js, simple-mock and nock
Grouping Allows organizing tests in groups	Yes You can create suites manually in spock	Yes Grouping is supported and is accomplished by the using a nested 'describe()'
Other Other useful information about the testing framework