# Test Execution and Observation Observe, introspect, and customize the test execution flow. ## Topics ### Test Failures Capture test failures with `XCTIssue` and related classes that associate source code locations and call stacks with failures. [`struct XCTIssue`](/documentation/XCTest/XCTIssue-swift.struct) An object that represents a test failure, and includes source code call stacks for test reporting and investigation. [`class XCTIssueReference`](/documentation/XCTest/XCTIssueReference) An object that represents a test failure, and includes source code call stacks for test reporting and investigation. [`class XCTMutableIssue`](/documentation/XCTest/XCTMutableIssue) A mutable object that represents a test failure, and includes source code call stacks for test reporting and investigation. [`class XCTSourceCodeContext`](/documentation/XCTest/XCTSourceCodeContext) An object that contains call stack and source code location details to provide context for a point of execution in a test. [`class XCTSourceCodeFrame`](/documentation/XCTest/XCTSourceCodeFrame) An object that represents a single frame in a call stack that supports retrieval of symbol information for the address. [`class XCTSourceCodeLocation`](/documentation/XCTest/XCTSourceCodeLocation) An object that contains a file URL and line number that represents a distinct location in source code. [`class XCTSourceCodeSymbolInfo`](/documentation/XCTest/XCTSourceCodeSymbolInfo) An object that contains symbolication information for a specified frame in a call stack. ### Test Runs [`class XCTestCaseRun`](/documentation/XCTest/XCTestCaseRun) An object that collects information about a specific execution of a test case. [`class XCTestSuiteRun`](/documentation/XCTest/XCTestSuiteRun) An object that collects information about a specific execution of a test suite. [`class XCTestRun`](/documentation/XCTest/XCTestRun) A base class for collecting information about a specific execution of a test. ### Test Observation [`protocol XCTestObservation`](/documentation/XCTest/XCTestObservation) A protocol that defines methods the test runner calls in response to significant events during test runs. [`class XCTestObservationCenter`](/documentation/XCTest/XCTestObservationCenter) Provides information about the progress of test runs to registered observers. ### Test Suites [`class XCTestSuite`](/documentation/XCTest/XCTestSuite) A collection of test cases to manage as a test suite. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)