# withKnownIssue(_:isIntermittent:isolation:sourceLocation:_:when:matching:) Invoke a function that has a known issue that is expected to occur during its execution. ``` func withKnownIssue(_ comment: Comment? = nil, isIntermittent: Bool = false, isolation: isolated (any Actor)? = #isolation, sourceLocation: SourceLocation = #_sourceLocation, _ body: () async throws -> Void, when precondition: () async -> Bool = { true }, matching issueMatcher: @escaping KnownIssueMatcher = { _ in true }) async rethrows ``` ## Parameters `comment` An optional comment describing the known issue. `isIntermittent` Whether or not the known issue occurs intermittently. If this argument is `true` and the known issue does not occur, no secondary issue is recorded. `isolation` The actor to which `body` is isolated, if any. `sourceLocation` The source location to which any recorded issues should be attributed. `body` The function to invoke. `precondition` A function that determines if issues are known to occur during the execution of `body`. If this function returns `true`, encountered issues that are matched by `issueMatcher` are considered to be known issues; if this function returns `false`, `issueMatcher` is not called and they are treated as unknown. `issueMatcher` A function to invoke when an issue occurs that is used to determine if the issue is known to occur. By default, all issues match. ## Discussion> Throws: Whatever is thrown by `body`, unless it is matched by > `issueMatcher`. Use this function when a test is known to record one or more issues that should not cause the test to fail, or if a precondition affects whether issues are known to occur. For example: ```swift @Test func example() async throws { try await withKnownIssue { try await flakyCall() } when: { callsAreFlakyOnThisPlatform() } matching: { issue in issue.error is FileNotFoundError } } ``` It is not necessary to specify both `precondition` and `issueMatcher` if only one is relevant. If all errors and issues should be considered known issues, use [`withKnownIssue(_:isIntermittent:isolation:sourceLocation:_:when:matching:)`](/documentation/Testing/withKnownIssue(_:isIntermittent:isolation:sourceLocation:_:when:matching:)) instead. > Note: `issueMatcher` may be invoked more than once for the same issue. ## See Also [Known issues](/documentation/Testing/known-issues) Mark issues as known when running tests. --- 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)