XCTest

XCTest is Apple’s framework for writing and running unit tests and performance tests in Xcode-based projects. It supports Swift and Objective-C code and is used for apps targeting iOS, macOS, tvOS, and watchOS. The framework provides a standardized way to validate code behavior and detect regressions during development and in CI workflows.

Tests in XCTest are organized into test cases, which are subclasses of XCTestCase. Test methods must begin with the prefix test. The framework offers setup and teardown methods that run before and after each test, including variants that can throw errors (setUpWithError and tearDownWithError in Swift). Tests are grouped into test suites and can be run individually or collectively through Xcode’s test navigator or command-line tools.

XCTest provides a range of assertion functions, such as XCTAssertTrue, XCTAssertFalse, XCTAssertEqual, XCTAssertNotNil, XCTAssertNil, and XCTAssertThrowsError, to verify expected outcomes. When an assertion fails, the test is marked as failed, and descriptive messages help diagnose the issue.

Asynchronous testing is supported via expectations (XCTestExpectation). Tests create expectations, fulfill them when the asynchronous task completes, and wait for fulfillment with wait(for:timeout:) or related APIs. Performance testing is done with measure, and optionally measure(metrics:) to collect specific metrics, enabling comparisons across runs.

XCTest integrates with Xcode schemes, Swift Package Manager, and CI pipelines. Tests can be authored in Swift or Objective-C within a test target. A related UI testing framework, XCUITest, builds on XCTest to automate user interface interactions. Overall, XCTest is the standard framework for validating code correctness and performance in Apple platforms.