Swift Testing Pro

1---2name: swift-testing-pro3description: Writes, reviews, and improves Swift Testing code using modern APIs and best practices. Use when reading, writing, or reviewing projects that use Swift Testing.4license: MIT5metadata:6  author: Paul Hudson7  version: "1.0"8---9 10Write and review Swift Testing code for correctness, modern API usage, and adherence to project conventions. Report only genuine problems - do not nitpick or invent issues.11 12Review process:13 141. Ensure tests follow core Swift Testing conventions using `references/core-rules.md`.151. Validate test structure, assertions, dependency injection, and other best practices using `references/writing-better-tests.md`.161. Check async tests, confirmations, time limits, actor isolation, and networking mocks using `references/async-tests.md`.171. Ensure new features like raw identifiers, test scopes, exit tests, and attachments are used correctly using `references/new-features.md`.181. If migrating from XCTest, follow the conversion guidance in `references/migrating-from-xctest.md`.19 20If doing partial work, load only the relevant reference files.21 22 23## Core Instructions24 25- Target Swift 6.2 or later, using modern Swift concurrency.26- As a Swift Testing developer, the user wants all new unit and integration tests to be written using Swift Testing, and they may ask for help migrating existing XCTest code to Swift Testing.27- Swift Testing does *not* support UI tests – XCTest must be used there.28- Use a consistent project structure, with folder layout determined by app features.29 30Swift Testing evolves with each Swift release, so expect three to four releases each year, each introducing new features. This means existing training data you have will naturally be outdated or missing key features.31 32This skill specifically draws upon the very latest Swift and Swift Testing code, which means it will suggest things you are not aware of. Treat the user’s installed toolchain as authoritative, but there's a fairly high chance Apple's *documentation* about the APIs will be stale, so treat them carefully.33 34 35## Output Format36 37If the user asks for a review, organize findings by file. For each issue:38 391. State the file and relevant line(s).402. Name the rule being violated.413. Show a brief before/after code fix.42 43Skip files with no issues. End with a prioritized summary of the most impactful changes to make first.44 45If the user asks you to write or improve tests, follow the same rules above but make the changes directly instead of returning a findings report.46 47Example output:48 49### UserTests.swift50 51**Line 5: Use struct, not class, for test suites.**52 53```swift54// Before55class UserTests: XCTestCase {56 57// After58struct UserTests {59```60 61**Line 12: Use `#expect` instead of `XCTAssertEqual`.**62 63```swift64// Before65XCTAssertEqual(user.name, "Taylor")66 67// After68#expect(user.name == "Taylor")69```70 71**Line 30: Use `#require` for preconditions, not `#expect`.**72 73```swift74// Before75#expect(users.isEmpty == false)76let first = users.first!77 78// After79let first = try #require(users.first)80```81 82### Summary83 841. **Fundamentals (high):** Test suite on line 5 should be a struct, not a class inheriting from `XCTestCase`.852. **Migration (medium):** `XCTAssertEqual` on line 12 should be migrated to `#expect`.863. **Assertions (medium):** Force-unwrap on line 30 should use `#require` to unwrap safely and stop the test early on failure.87 88End of example.89 90 91## References92 93- `references/core-rules.md` - core Swift Testing rules: structs over classes, `init`/`deinit` over setUp/tearDown, parallel execution, parameterized tests, `withKnownIssue`, and tags.94- `references/writing-better-tests.md` - test hygiene, structuring tests, hidden dependencies, `#expect` vs `#require`, `Issue.record()`, `#expect(throws:)`, and verification methods.95- `references/async-tests.md` - serialized tests, `confirmation()`, time limits, actor isolation, testing pre-concurrency code, and mocking networking.96- `references/new-features.md` - raw identifiers, range-based confirmations, test scoping traits, exit tests, attachments, `ConditionTrait.evaluate()`, and the updated `#expect(throws:)` return value.97- `references/migrating-from-xctest.md` - XCTest-to-Swift Testing conversion steps, assertion mappings, and floating-point tolerance via Swift Numerics.