how does swift testing work

Swift Testing is a modern, open-source testing framework designed specifically for Swift. It offers expressive APIs that simplify the process of writing tests and is cross-platform, supporting all Apple operating systems that support Swift concurrency, as well as Linux and Windows. Here are some key features and aspects of Swift Testing:

1. Expressive APIs: Swift Testing allows you to write tests using expressive APIs. You can use the @test attribute to declare test functions and provide custom display names to make tests more understandable.

2. Cross-Platform Consistency: Unlike XCTest, which had multiple implementations, Swift Testing has a common codebase across platforms, ensuring consistent behavior and better functional parity.

3. Integration with Tools: Swift Testing is integrated into major tools and IDEs in the Swift ecosystem, including the Swift Package Manager, Xcode 16, and Visual Studio Code with the Swift extension.

4. Parallel Testing: Swift Testing takes advantage of Swift's concurrency features to run tests in parallel, which can significantly reduce the time it takes to run your tests.

5. Open Source and Community-Driven: Swift Testing is open source and hosted on GitHub. It has an open feature proposal process, and its evolution is discussed on the Swift forum, inviting community involvement.

6. Migration from XCTest: If you have existing XCTest tests, Swift Testing provides guidance on how to migrate them, including translating assertions and handling asynchronous conditions.

7. Parameterized and Tagged Tests: You can parameterize tests to reuse the same logic across different values and use tags to organize and selectively run tests.

For more detailed information, you can refer to the sessions "Meet Swift Testing" and "Go further with Swift Testing" from WWDC 2024. If you're interested in the introduction of Swift Testing, you can check out the Platforms State of the Union (33:12) session.