# confirmation(_:expectedCount:isolation:sourceLocation:_:) Confirm that some event occurs during the invocation of a function. ``` func confirmation(_ comment: Comment? = nil, expectedCount: some RangeExpression & Sendable & Sequence, isolation: isolated (any Actor)? = #isolation, sourceLocation: SourceLocation = #_sourceLocation, _ body: (Confirmation) async throws -> sending R) async rethrows -> R ``` ## Parameters `comment` An optional comment to apply to any issues generated by this function. `expectedCount` A range of integers indicating the number of times the expected event should occur when `body` is invoked. `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. ## Return Value Whatever is returned by `body`. ## Discussion> Throws: Whatever is thrown by `body`. Use confirmations to check that an event occurs while a test is running in complex scenarios where `#expect()` and `#require()` are insufficient. For example, a confirmation may be useful when an expected event occurs: - In a context that cannot be awaited by the calling function such as an event handler or delegate callback; - More than once, or never; or - As a callback that is invoked as part of a larger operation. To use a confirmation, pass a closure containing the work to be performed. The testing library will then pass an instance of [`Confirmation`](/documentation/Testing/Confirmation) to the closure. Every time the event in question occurs, the closure should call the confirmation: ```swift let minBuns = 5 let maxBuns = 10 await confirmation( "Baked between \(minBuns) and \(maxBuns) buns", expectedCount: minBuns ... maxBuns ) { bunBaked in foodTruck.eventHandler = { event in if event == .baked(.cinnamonBun) { bunBaked() } } await foodTruck.bakeTray(of: .cinnamonBun) } ``` When the closure returns, the testing library checks if the confirmation’s preconditions have been met, and records an issue if they have not. If an exact count is expected, use [`confirmation(_:expectedCount:isolation:sourceLocation:_:)`](/documentation/Testing/confirmation(_:expectedCount:isolation:sourceLocation:_:)-5mqz2) instead. --- 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)