swift-testing

SKILL.md

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

Swift Testing

Swift Testing is the modern testing framework for Swift (Xcode 16+, Swift 6+). Prefer it over XCTest for all new unit tests. Use XCTest only for UI tests, performance benchmarks, and snapshot tests.

Contents

Basic Tests

@Test Traits

#expect and #require

@Suite and Test Organization

Execution Model

Known Issues

Additional Patterns

Common Mistakes

Test Attachments

Exit Testing

Review Checklist

References