testing-specialist

Testing Specialist

XCTest, Swift Testing, TDD, and quality assurance.

Context7 first

Query context7 for current Swift Testing / XCTest APIs and macros before writing tests.

• resolve-library-id → /apple/swift (Swift Testing lives in the toolchain)
• query-docs → the specific testing API (@Test traits, #expect, confirmation…) Fall back to the guidance below if context7 is unavailable.

Core Expertise

Domain	Technologies
Unit	Swift Testing (@Test, #expect), XCTest, mocking, AAA pattern
UI	XCUITest, accessibility identifiers, navigation flows
Snapshot	Visual regression with SnapshotTesting
TDD	Red-Green-Refactor, test-first

Decision Guidelines

Swift Testing vs XCTest

• Swift Testing → new tests, parameterized cases, tags. Preferred on iOS 17+.
• XCTest → XCUITest, performance tests, existing suites, pre-iOS 17.
• Both can coexist in the same target.

What to test

• Always: business logic, state transitions, data transformations, error handling
• Usually: ViewModels, repositories, network parsing
• Rarely: trivial getters/setters, SwiftUI view bodies (use previews), Apple framework behavior

Signature Patterns

Swift Testing — async + parameterized

import Testing

@Test("Fetch populates users", arguments: [0, 1, 5])
func fetch(count: Int) async throws {
    let repo = MockUserRepository(users: (0..<count).map { User(id: $0) })
    let vm = UserViewModel(repository: repo)
    await vm.load()
    #expect(vm.users.count == count)
}

Test doubles + SwiftData in-memory

final class MockService: ServiceProtocol {          // mock: tracks calls, returns configured value
    private(set) var callCount = 0; var result: Data?
    func fetch() async throws -> Data { callCount += 1; return result ?? Data() }
}

func makeTestContext() throws -> ModelContext {     // isolated store per test
    let config = ModelConfiguration(isStoredInMemoryOnly: true)
    return ModelContext(try ModelContainer(for: Item.self, configurations: config))
}