Spock vs Buster.JS comparison of testing frameworks
What are the differences between Spock and Buster.JS?

Spock

http://spockframework.org/

Buster.JS

https://busterjs.readthedocs.io
Programming language

Java

JavaScript

Category

Unit Testing

Unit Testing, Browser Automation

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

Buster.JS is a JavaScript test framework for node and browsers.

Buster.JS is a new JavaScript testing framework. It does browser testing by automating test runs in actual browsers (think JsTestDriver), as well as Node.js testing. It has a bunch of great features.
xUnit
Set of frameworks originating from SUnit (Smalltalk's testing framework). They share similar structure and functionality.

No

Yes

Buster.Js is a xUnit style Test Framework
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

It does browser testing with browser automation, QUnit style static HTML page testing, testing in headless browsers and more front-end components and functionality
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

It is a Node.js testing toolkit as well which means it can test back-end behaviour and functionality as well as run in a server environment
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)

N/A

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

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

BSD 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

Buster.JS ships with Sinon.JS. every test in a test case has a sandbox associated with it, making it easy to mock and stub
Grouping
Allows organizing tests in groups

Yes

You can create suites manually in spock

Other
Other useful information about the testing framework