# Publishers.AssertNoFailure A publisher that raises a fatal error upon receiving any failure, and otherwise republishes all received input. ``` struct AssertNoFailure where Upstream : Publisher ``` ## Overview Use this function for internal integrity checks that are active during testing but don’t affect performance of shipping code. ## Topics ### Creating an assert no failure publisher [`init(upstream:prefix:file:line:)`](/documentation/Combine/Publishers/AssertNoFailure/init(upstream:prefix:file:line:)) Creates a publisher that raises a fatal error upon receiving any failure, and otherwise republishes all received input. ### Declaring supporting types [`Publishers.AssertNoFailure.Output`](/documentation/Combine/Publishers/AssertNoFailure/Output) The kind of values published by this publisher. [`Publishers.AssertNoFailure.Failure`](/documentation/Combine/Publishers/AssertNoFailure/Failure) The kind of errors this publisher might publish. ### Inspecting publisher properties [`upstream`](/documentation/Combine/Publishers/AssertNoFailure/upstream) The publisher from which this publisher receives elements. [`file`](/documentation/Combine/Publishers/AssertNoFailure/file) The filename used in the error message. [`line`](/documentation/Combine/Publishers/AssertNoFailure/line) The line number used in the error message. [`prefix`](/documentation/Combine/Publishers/AssertNoFailure/prefix) The string used at the beginning of the fatal error message. --- 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)