Modern Swift testing framework with @Test macros, parameterized tests, traits, and async support.

• Write unit tests using @Test macros with #expect and #require assertions; prefer Swift Testing over XCTest for all new tests (Xcode 16+, Swift 6+)
• Organize tests with @Suite for grouping, custom tags for filtering, and traits for conditional execution, time limits, and known issues
• Support parameterized tests via arguments: with enum cases, ranges, or cartesian products; use confirmation() to verify async callbacks without sleep
• Handle async/await patterns natively, test error paths with throws: expectations, and manage actor-isolated state with await