# AttachableWrapper A protocol describing a type whose instances can be recorded and saved as part of a test run and which contains another value that it stands in for. ``` protocol AttachableWrapper : Attachable, ~Copyable ``` ## Overview To attach an attachable value to a test, pass it to [`record(_:named:sourceLocation:)`](/documentation/Testing/Attachment/record(_:named:sourceLocation:)). To further configure an attachable value before you attach it, use it to initialize an instance of [`Attachment`](/documentation/Testing/Attachment) and set its properties before passing it to [`record(_:sourceLocation:)`](/documentation/Testing/Attachment/record(_:sourceLocation:)). An attachable value can only be attached to a test once. A type can conform to this protocol if it represents another type that cannot directly conform to [`Attachable`](/documentation/Testing/Attachable), such as a non-final class or a type declared in a third-party module. ## Topics ### Associated Types [`associatedtype Wrapped`](/documentation/Testing/AttachableWrapper/Wrapped) The type of the underlying value represented by this type. ### Instance Properties [`var wrappedValue: Self.Wrapped`](/documentation/Testing/AttachableWrapper/wrappedValue) The underlying value represented by this instance. ## Relationships ### Inherits From [`Attachable`](/documentation/Testing/Attachable) --- 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)