JUnit vs Kotest: What are the differences?

Differences between JUnit and Kotest in Markdown

JUnit and Kotest are both popular testing frameworks used in the Java ecosystem. However, there are several key differences between the two.

1. Test Execution: JUnit follows a sequential test execution approach, where each test method is executed one after another in a predetermined order. On the other hand, Kotest allows for parallel test execution, enabling multiple test methods to run concurrently.

2. Assertions: JUnit provides a limited set of built-in assertions, such as assertEquals and assertTrue. In contrast, Kotest offers an extensive range of assertion functions with more expressive syntax, including should, shouldNotBe, and shouldBeTypeOf, which make the tests more readable and easier to understand.

3. Extensions and Interceptors: JUnit uses the concept of rules or extensions to provide additional test features, such as defining timeouts or managing resources. In Kotest, interceptors are used to intercept and modify the behavior of tests. This allows for more flexibility and customization in test workflows.

4. Tagging and Filtering: Kotest supports tagging of tests using annotations, allowing for easy categorization and filtering of tests based on specific criteria. JUnit, on the other hand, does not have built-in support for tagging or filtering tests.

5. Testing Styles: JUnit primarily follows a method-level testing style, where each test case is represented by a separate method. In Kotest, a more explicit and flexible testing style called "behaviour-spec style" is supported, where tests are defined using lambdas and can be organized hierarchically.

6. Interoperability: JUnit is widely adopted and integrated with various IDEs, build tools, and test frameworks, making it easier to integrate into existing projects. Although Kotest is gaining popularity, its ecosystem is still growing, and it might require additional effort to integrate with existing tools and frameworks.

In summary, JUnit and Kotest differ in their test execution approaches, assertion capabilities, extension mechanisms, tagging and filtering support, testing styles, and interoperability.