swift-testing

name	swift-testing
description	Standards for XCTest, Async Tests, and Test Organization. Use when writing XCTest cases, async tests, or organizing test suites in Swift. (triggers: **/*Tests.swift, XCTestCase, XCTestExpectation, XCTAssert)

Swift Testing Standards

Priority: P0

Implementation Guidelines

XCTest Framework

• Standard Naming: Test functions must be prefixed by 'test' (e.g., func testUserLoginSuccessful()).
• Setup/Teardown: Use setUpWithError() and tearDownWithError() for environment management.
• Assertions: Use specific assertions: XCTAssertEqual, XCTAssertNil, XCTAssertTrue, etc.

Async Testing

• Async/Await: Mark test methods as async throws and use try await directly inside them.
• Expectations: Use XCTestExpectation for callback-based async logic. Call expectation then fulfill() when done; then wait(for: [exp], timeout: 2.0) to block.
• Timeout: Always set reasonable timeouts for expectations to avoid hanging CI.

Test Organization

• Unit Tests: Use protocols for dependencies and Inject them via constructor (e.g., init(service: ServiceProtocol)). Focus on logic isolation using mocks/stubs.
• UI Tests: Test user flows using XCUIApplication and accessibility identifiers.
• Coverage: Aim for high coverage on critical business logic and state transitions.

Anti-Patterns

• No Thread.sleep: Use expectations or await.
• No force unwrap in tests: Use XCTUnwrap() for better failure messages.
• No assertion-free tests: A test that only runs code is not a test.

References

• XCTest Patterns & Async Tests