Spek vs Cucumber-JVM comparison of testing frameworks
What are the differences between Spek and Cucumber-JVM?

	Spek https://www.spekframework.org/	Cucumber-JVM https://github.com/cucumber/cucumber-jvm
Programming language	Kotlin	Java
Category	Acceptance Testing, Unit Testing	Acceptance Testing
General info	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.	Cucumber-JVM is a pure Java implementation of Cucumber The specifications are written in plain texts, which allows them to be easily understandable by all stakeholders.
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 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.	Yes You can test the front-end part like the GUI using cucumber with serenity, they integrate well to test your front-end.
Server-side Allows testing the bahovior of a server-side code	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	Yes You can test back-end components such as API's using rest&soap clients, and databases
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 available in spek through functions suchas beforeEachTest() and afterEachTest()	Yes Using the cucumber extension aruba you can create fixures in two steps: 1.Create a fixtures-directory; 2.Create fixture files in this directory
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 spek has group fixtures available through the beforeGroup() and afterGroup() functions	Yes You can group your fixtures inside your fixtures directories
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	Modified BSD License	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 You can use the third party library mockito-kotlin	Yes By using all of RSpec’s supported mocking frameworks (RSpec, Mocha, RR, Flexmock)
Grouping Allows organizing tests in groups	Yes Tests are written using nested lambdas, each scope (level) can either be a group or a test	Yes Cucumber allows the use of tag Cucumber feature files or individual tests to group tests. Then, you can pass a Cucumber tagged expression at test execution that specifies the tag (grouped) tests to run. https://www.toolsqa.com/cucumber/cucumber-tags/
Other Other useful information about the testing framework