Swift Unit Testing

Build deterministic tests around observable behavior. Prefer Swift Testing for new Swift unit and integration tests; choose XCTest only where it still provides the required runner or API.

Compatibility baseline

• Swift Testing requires Swift 6 / Xcode 16 or newer. It supports Apple platforms, Linux, and Windows.
• XCTest remains appropriate for XCUIApplication, XCTMetric, Objective-C tests, and incremental maintenance of existing XCTest suites.
• Swift Testing and XCTest can coexist in one test target. Do not mix @Test methods into an XCTestCase subclass.
• State the app's actual deployment targets and CI Xcode version before recommending availability-sensitive traits or APIs.
• Treat APIs first introduced after the installed SDK as future-cycle features and gate them explicitly.

Select the test layer