JUnit vs Spek comparison of testing frameworks
What are the differences between JUnit and Spek?

JUnit

https://junit.org/junit5/

Spek

https://www.spekframework.org/
Programming language

Java

Kotlin

Category

Unit Testing, Regression Testing

Acceptance Testing, Unit Testing

General info

JUnit is an open source Unit testing framework for java

JUnit is useful for developers to write and run repeatable tests. JUnit has been crucial in the development of test driven development and is partof the xUnit family of unit testing frameworks

Spek is a specification framework for Kotlin

Spek is a Kotlin-based Specification Testing framework for the JVM. It works as a JUnit 5 Test Engine meaning that we can easily plug it into any project that already uses JUnit 5 to run alongside any other tests that we might have.
xUnit
Set of frameworks originating from SUnit (Smalltalk's testing framework). They share similar structure and functionality.

Yes

It is an instance of the xUnit architecture for unit testing frameworks.

No

Client-side
Allows testing code execution on the client, such as a web browser

Yes

You can test front-end components such as individual classes and functions that create the front-end

Yes

Yes you can test front-end behaviour by writing specifications to test front-end functionality. Developers can also write unit tests for individual front-end components.
Server-side
Allows testing the bahovior of a server-side code

Yes

You can test classes and functions that compose the back-end such as database connections and so on

Yes

You can test back-end behaviour and componets by writing specifications to test back-end functionality and unit tests for individual back-end components
Fixtures
Allows defining a fixed, specific states of data (fixtures) that are test-local. This ensures specific environment for a single test

Yes

JUnit contains a setUp() method, which runs before every test invocation and a tearDown() method, which runs after every test method.

Yes

Fixtures are available in spek through functions suchas beforeEachTest() and afterEachTest()
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 setUp() and tearDown() inbuilt functions as group fixtures.

Yes

spek has group fixtures available through the beforeGroup() and afterGroup() functions
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.

You can use JUnit-quickcheck to generate test data

N/A

Licence
Licence type governing the use and redistribution of the software

Modified 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)

JUnit does not support mocking internally but you can use a mock framework like Mockito to generate mock objects.

Yes

You can use the third party library mockito-kotlin
Grouping
Allows organizing tests in groups

Yes

In JUnit you can create a test suite that bundles a few unit test cases and runs them together. You use both @RunWith and @Suite annotation are used to run the suite test.

Yes

Tests are written using nested lambdas, each scope (level) can either be a group or a test
Other
Other useful information about the testing framework