การตั้งค่า การล้างข้อมูล และเมธอดการทดสอบของ XCTestCase

import XCTest

final class MathTests: XCTestCase {
  func testAddition() {
    XCTAssertEqual(2 + 2, 4)
  }
}

final class UserServiceTests: XCTestCase {
  var sut: UserService!
  override func setUp() {
    super.setUp()
    sut = UserService()
  }
  override func tearDown() {
    sut = nil
    super.tearDown()
  }
}

override func setUpWithError() throws {
  sut = try UserService(config: loadTestConfig())
}
override func tearDownWithError() throws {
  try sut.cleanup()
}

final class DBTests: XCTestCase {
  static var db: TestDatabase!
  override class func setUp() {
    super.setUp()
    db = TestDatabase.inMemory()
  }
  override class func tearDown() {
    db.close()
    super.tearDown()
  }
}

func test_login_withValidCredentials_returnsUser() throws { ... }
func test_login_withInvalidPassword_throwsUnauthorized() throws { ... }

func testCreateFile() throws {
  let url = FileManager.default.temporaryDirectory.appendingPathComponent("test.txt")
  addTeardownBlock { try? FileManager.default.removeItem(at: url) }
  // ... test
}

func testExperimentalFeature() throws {
  try XCTSkipIf(ProcessInfo.processInfo.environment["CI"] != nil, "Skip on CI")
  // ... test
}

func testDecode() throws {
  let user = try JSONDecoder().decode(User.self, from: validJSON)
  XCTAssertEqual(user.name, "Alice")
}

func testCallback() {
  var called = false
  service.doWork { called = true }
  if !called { XCTFail("Callback was never invoked") }
}

// File → New → Test Plan
// Add test targets and configure per-configuration env vars
// Useful for running localized UI tests or with Address Sanitizer

// Product → Scheme → Test → Options → Execute in parallel
// Each XCTestCase class runs in a separate process
// Ensure tests are independent and don't share global state