---
title: "withKnownIssue(_:isIntermittent:sourceLocation:_:when:matching:)"
framework: testing
role: symbol
role_heading: Function
path: "testing/withknownissue(_:isintermittent:sourcelocation:_:when:matching:)"
---

# withKnownIssue(_:isIntermittent:sourceLocation:_:when:matching:)

Invoke a function that has a known issue that is expected to occur during its execution.

## Declaration

```swift
func withKnownIssue(_ comment: Comment? = nil, isIntermittent: Bool = false, sourceLocation: SourceLocation = #_sourceLocation, _ body: () throws -> Void, when precondition: () -> Bool = { true }, matching issueMatcher: @escaping KnownIssueMatcher = { _ in true }) 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.
- `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.

## Mentioned in

Migrating a test from XCTest

## Discussion

Discussion note: 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: @Test func example() throws {   try withKnownIssue {     try 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:sourceLocation:_:) instead. note: issueMatcher may be invoked more than once for the same issue.

## See Also

### Related Documentation

- [Known issues](testing/known-issues.md)

### Recording known issues in tests

- [withKnownIssue(_:isIntermittent:sourceLocation:_:)](testing/withknownissue(_:isintermittent:sourcelocation:_:).md)
- [withKnownIssue(_:isIntermittent:isolation:sourceLocation:_:)](testing/withknownissue(_:isintermittent:isolation:sourcelocation:_:).md)
- [withKnownIssue(_:isIntermittent:isolation:sourceLocation:_:when:matching:)](testing/withknownissue(_:isintermittent:isolation:sourcelocation:_:when:matching:).md)
- [KnownIssueMatcher](testing/knownissuematcher.md)