# XCTestObservation A protocol that defines methods the test runner calls in response to significant events during test runs. ``` protocol XCTestObservation : NSObjectProtocol ``` ## Overview The system calls the notification methods for [`XCTestObservation`](/documentation/XCTest/XCTestObservation) in the following sequence for a test bundle: 1. [`testBundleWillStart(_:)`](/documentation/XCTest/XCTestObservation/testBundleWillStart(_:)) — exactly once per test bundle 2. [`testSuiteWillStart(_:)`](/documentation/XCTest/XCTestObservation/testSuiteWillStart(_:)) — exactly once per test suite 3. [`testCaseWillStart(_:)`](/documentation/XCTest/XCTestObservation/testCaseWillStart(_:)) — exactly once per test case 4. [`testCase(_:didRecord:)`](/documentation/XCTest/XCTestObservation/testCase(_:didRecord:)-4cou6) — for each test failure, zero or more times per test case at any point between test case start and finish 5. [`testCase(_:didRecord:)`](/documentation/XCTest/XCTestObservation/testCase(_:didRecord:)-8k955) — for each expected test failure, zero or more times per test case at any point between test case start and finish 6. [`testCaseDidFinish(_:)`](/documentation/XCTest/XCTestObservation/testCaseDidFinish(_:)) — exactly once per test case 7. [`testSuite(_:didRecord:)`](/documentation/XCTest/XCTestObservation/testSuite(_:didRecord:)-3rk9k) — for each test failure, zero or more times per test suite at any point between test suite start and finish 8. [`testSuite(_:didRecord:)`](/documentation/XCTest/XCTestObservation/testSuite(_:didRecord:)-1xjkv) — for each expected test failure, zero or more times per test suite at any point between test suite start and finish 9. [`testSuiteDidFinish(_:)`](/documentation/XCTest/XCTestObservation/testSuiteDidFinish(_:)) — exactly once per test suite 10. [`testBundleDidFinish(_:)`](/documentation/XCTest/XCTestObservation/testBundleDidFinish(_:)) — exactly once per test bundle See [`XCTestObservationCenter`](/documentation/XCTest/XCTestObservationCenter) for details about registering and removing test observers. ## Topics ### Observation Methods [`testBundleWillStart(_:)`](/documentation/XCTest/XCTestObservation/testBundleWillStart(_:)) Notifies the observer immediately before any tests in a test bundle begin. [`testSuiteWillStart(_:)`](/documentation/XCTest/XCTestObservation/testSuiteWillStart(_:)) Notifies the observer immediately before a test suite begins executing. [`testCaseWillStart(_:)`](/documentation/XCTest/XCTestObservation/testCaseWillStart(_:)) Notifies the observer immediately before a test case begins executing. [`testCase(_:didRecord:)`](/documentation/XCTest/XCTestObservation/testCase(_:didRecord:)-4cou6) Notifies the observer when a test case reports an issue. [`testCase(_:didRecord:)`](/documentation/XCTest/XCTestObservation/testCase(_:didRecord:)-8k955) Notifies the observer when a test case records an expected failure. [`testCase(_:didFailWithDescription:inFile:atLine:)`](/documentation/XCTest/XCTestObservation/testCase(_:didFailWithDescription:inFile:atLine:)) Notifies the observer when a test case reports a failure. [`testCaseDidFinish(_:)`](/documentation/XCTest/XCTestObservation/testCaseDidFinish(_:)) Notifies the observer immediately after a test case finishes executing. [`testSuite(_:didRecord:)`](/documentation/XCTest/XCTestObservation/testSuite(_:didRecord:)-3rk9k) Notifies the observer when a test suite reports an issue. [`testSuite(_:didRecord:)`](/documentation/XCTest/XCTestObservation/testSuite(_:didRecord:)-1xjkv) Notifies the observer when a test suite records an expected failure. [`testSuite(_:didFailWithDescription:inFile:atLine:)`](/documentation/XCTest/XCTestObservation/testSuite(_:didFailWithDescription:inFile:atLine:)) Notifies the observer when a test suite reports a failure. [`testSuiteDidFinish(_:)`](/documentation/XCTest/XCTestObservation/testSuiteDidFinish(_:)) Notifies the observer immediately after a test suite finishes executing. [`testBundleDidFinish(_:)`](/documentation/XCTest/XCTestObservation/testBundleDidFinish(_:)) Notifies the observer immediately after all tests in a test bundle finish executing. --- 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)