swift-testing-code-review

Check that #expect embeds expressions directly rather than pre-computed booleans, #require is used only for preconditions, and parameterized tests use zip() for paired arguments. Also verify async tests use confirmation for streams and withCheckedContinuation for completion handlers.

#expect is a soft assertion that records a failure and continues execution, while #require is a hard precondition that stops the test immediately on failure. Use #require only when subsequent code cannot proceed without the value, such as unwrapping an optional.

Passing multiple arrays to @Test(arguments:) creates a Cartesian product of all combinations. Wrap the arrays in zip() to pair elements one-to-one, but ensure equal lengths since zip silently drops extra elements.

No, confirmation uses eager evaluation and the closure exits before the callback fires. Use withCheckedContinuation to convert the callback into awaitable async code, or use XCTest's fulfillment(of:timeout:) for callback-style waiting.

Apply .serialized only when tests share limited resources like databases or external services, since Swift Testing runs tests in parallel by default. Sibling serialized suites that must be mutually exclusive should be nested under a shared parent suite.