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Attachment lifetimes #1319

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3ba41e0
Attachment lifetimes
grynspan Sep 16, 2025
3ef8b2f
Fix some test terminology
grynspan Sep 16, 2025
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31 changes: 15 additions & 16 deletions Sources/Testing/Attachments/Attachable.swift
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Expand Up @@ -8,14 +8,15 @@
// See https://swift.org/CONTRIBUTORS.txt for Swift project authors
//

/// A protocol describing a type that can be attached to a test report or
/// written to disk when a test is run.
private import _TestingInternals

/// A protocol describing a type whose instances can be recorded and saved as
/// part of a test run.
///
/// To attach an attachable value to a test, pass it to ``Attachment/record(_:named:sourceLocation:)``.
/// To further configure an attachable value before you attach it, use it to
/// initialize an instance of ``Attachment`` and set its properties before
/// passing it to ``Attachment/record(_:sourceLocation:)``. An attachable
/// value can only be attached to a test once.
/// passing it to ``Attachment/record(_:sourceLocation:)``.
///
/// The testing library provides default conformances to this protocol for a
/// variety of standard library types. Most user-defined types do not need to
Expand All @@ -36,8 +37,8 @@ public protocol Attachable: ~Copyable {
/// an attachment.
///
/// The testing library uses this property to determine if an attachment
/// should be held in memory or should be immediately persisted to storage.
/// Larger attachments are more likely to be persisted, but the algorithm the
/// should be held in memory or should be immediately saved. Larger
/// attachments are more likely to be saved immediately, but the algorithm the
/// testing library uses is an implementation detail and is subject to change.
///
/// The value of this property is approximately equal to the number of bytes
Expand Down Expand Up @@ -66,13 +67,12 @@ public protocol Attachable: ~Copyable {
/// - Throws: Whatever is thrown by `body`, or any error that prevented the
/// creation of the buffer.
///
/// The testing library uses this function when writing an attachment to a
/// test report or to a file on disk. The format of the buffer is
/// implementation-defined, but should be "idiomatic" for this type: for
/// example, if this type represents an image, it would be appropriate for
/// the buffer to contain an image in PNG format, JPEG format, etc., but it
/// would not be idiomatic for the buffer to contain a textual description of
/// the image.
/// The testing library uses this function when saving an attachment. The
/// format of the buffer is implementation-defined, but should be "idiomatic"
/// for this type: for example, if this type represents an image, it would be
/// appropriate for the buffer to contain an image in PNG format, JPEG format,
/// etc., but it would not be idiomatic for the buffer to contain a textual
/// description of the image.
///
/// @Metadata {
/// @Available(Swift, introduced: 6.2)
Expand All @@ -91,9 +91,8 @@ public protocol Attachable: ~Copyable {
/// - Returns: The preferred name for `attachment`.
///
/// The testing library uses this function to determine the best name to use
/// when adding `attachment` to a test report or persisting it to storage. The
/// default implementation of this function returns `suggestedName` without
/// any changes.
/// when saving `attachment`. The default implementation of this function
/// returns `suggestedName` without any changes.
///
/// @Metadata {
/// @Available(Swift, introduced: 6.2)
Expand Down
5 changes: 2 additions & 3 deletions Sources/Testing/Attachments/AttachableWrapper.swift
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Expand Up @@ -8,9 +8,8 @@
// See https://swift.org/CONTRIBUTORS.txt for Swift project authors
//

/// A protocol describing a type that can be attached to a test report or
/// written to disk when a test is run and which contains another value that it
/// stands in for.
/// 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.
///
/// To attach an attachable value to a test, pass it to ``Attachment/record(_:named:sourceLocation:)``.
/// To further configure an attachable value before you attach it, use it to
Expand Down
122 changes: 67 additions & 55 deletions Sources/Testing/Attachments/Attachment.swift
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Expand Up @@ -13,11 +13,24 @@ private import _TestingInternals
/// A type describing values that can be attached to the output of a test run
/// and inspected later by the user.
///
/// Attachments are included in test reports in Xcode or written to disk when
/// tests are run at the command line. To create an attachment, you need a value
/// of some type that conforms to ``Attachable``. Initialize an instance of
/// ``Attachment`` with that value and, optionally, a preferred filename to use
/// when writing to disk.
/// To create an attachment, you need a value of some type that conforms to
/// ``Attachable``. Initialize an instance of ``Attachment`` with that value
/// and, optionally, a preferred filename to use when saving the attachment. To
/// record the attachment, call ``Attachment/record(_:sourceLocation:)``.
/// Alternatively, pass your attachable value directly to ``Attachment/record(_:named:sourceLocation:)``.
///
/// By default, the testing library saves your attachments as soon as you call
/// ``Attachment/record(_:sourceLocation:)`` or
/// ``Attachment/record(_:named:sourceLocation:)``. You can access saved
/// attachments after your tests finish running:
///
/// - When using Xcode, you can access attachments from the test report.
/// - When using Visual Studio Code, the testing library saves attachments to
/// `.build/attachments` by default. Visual Studio Code reports the paths to
/// individual attachments in its Tests Results panel.
/// - When using Swift Package Manager's `swift test` command, you can pass the
/// `--attachments-path` option and the testing library will save attachments
/// to the specified directory.
///
/// @Metadata {
/// @Available(Swift, introduced: 6.2)
Expand All @@ -41,16 +54,17 @@ public struct Attachment<AttachableValue> where AttachableValue: Attachable & ~C
/// Storage for ``attachableValue-7dyjv``.
private var _storage: Storage

/// The path to which the this attachment was written, if any.
/// The path to which the this attachment was saved, if any.
///
/// If a developer sets the ``Configuration/attachmentsPath`` property of the
/// current configuration before running tests, or if a developer passes
/// `--attachments-path` on the command line, then attachments will be
/// automatically written to disk when they are attached and the value of this
/// property will describe the path where they were written.
/// automatically saved when they are attached and the value of this property
/// will describe the paths where they were saved. A developer can use the
/// ``AttachmentSavingTrait`` trait type to defer or skip saving attachments.
///
/// If no destination path is set, or if an error occurred while writing this
/// attachment to disk, the value of this property is `nil`.
/// If no destination path is set, or if an error occurred while saving this
/// attachment, the value of this property is `nil`.
@_spi(ForToolsIntegrationOnly)
public var fileSystemPath: String?

Expand All @@ -62,8 +76,7 @@ public struct Attachment<AttachableValue> where AttachableValue: Attachable & ~C
/// Storage for ``preferredName``.
fileprivate var _preferredName: String?

/// A filename to use when writing this attachment to a test report or to a
/// file on disk.
/// A filename to use when saving this attachment.
///
/// The value of this property is used as a hint to the testing library. The
/// testing library may substitute a different filename as needed. If the
Expand Down Expand Up @@ -106,9 +119,9 @@ extension Attachment where AttachableValue: ~Copyable {
/// - Parameters:
/// - attachableValue: The value that will be attached to the output of the
/// test run.
/// - preferredName: The preferred name of the attachment when writing it to
/// a test report or to disk. If `nil`, the testing library attempts to
/// derive a reasonable filename for the attached value.
/// - preferredName: The preferred name of the attachment to use when saving
/// it. If `nil`, the testing library attempts to generate a reasonable
/// filename for the attached value.
/// - sourceLocation: The source location of the call to this initializer.
/// This value is used when recording issues associated with the
/// attachment.
Expand Down Expand Up @@ -248,11 +261,11 @@ extension Attachment where AttachableValue: Sendable & ~Copyable {
///
/// When `attachableValue` is an instance of a type that does not conform to
/// the [`Sendable`](https://developer.apple.com/documentation/swift/sendable)
/// protocol, the testing library encodes it as data immediately. If
/// `attachableValue` throws an error when the testing library attempts to
/// encode it, the testing library records that error as an issue in the
/// current test and does not write the attachment to the test report or to
/// persistent storage.
/// protocol, the testing library calls its ``Attachable/withUnsafeBytes(for:_:)``
/// immediately and records a copy of the resulting buffer instead. If
/// `attachableValue` throws an error when the testing library calls its
/// ``Attachable/withUnsafeBytes(for:_:)`` function, the testing library
/// records that error as an issue in the current test.
///
/// @Metadata {
/// @Available(Swift, introduced: 6.2)
Expand All @@ -273,18 +286,18 @@ extension Attachment where AttachableValue: Sendable & ~Copyable {
///
/// - Parameters:
/// - attachableValue: The value to attach.
/// - preferredName: The preferred name of the attachment when writing it to
/// a test report or to disk. If `nil`, the testing library attempts to
/// derive a reasonable filename for the attached value.
/// - preferredName: The preferred name of the attachment to use when saving
/// it. If `nil`, the testing library attempts to generate a reasonable
/// filename for the attached value.
/// - sourceLocation: The source location of the call to this function.
///
/// When `attachableValue` is an instance of a type that does not conform to
/// the [`Sendable`](https://developer.apple.com/documentation/swift/sendable)
/// protocol, the testing library encodes it as data immediately. If
/// `attachableValue` throws an error when the testing library attempts to
/// encode it, the testing library records that error as an issue in the
/// current test and does not write the attachment to the test report or to
/// persistent storage.
/// protocol, the testing library calls its ``Attachable/withUnsafeBytes(for:_:)``
/// immediately and records a copy of the resulting buffer instead. If
/// `attachableValue` throws an error when the testing library calls its
/// ``Attachable/withUnsafeBytes(for:_:)`` function, the testing library
/// records that error as an issue in the current test.
///
/// This function creates a new instance of ``Attachment`` and immediately
/// attaches it to the current test.
Expand All @@ -308,11 +321,11 @@ extension Attachment where AttachableValue: ~Copyable {
///
/// When `attachableValue` is an instance of a type that does not conform to
/// the [`Sendable`](https://developer.apple.com/documentation/swift/sendable)
/// protocol, the testing library encodes it as data immediately. If
/// `attachableValue` throws an error when the testing library attempts to
/// encode it, the testing library records that error as an issue in the
/// current test and does not write the attachment to the test report or to
/// persistent storage.
/// protocol, the testing library calls its ``Attachable/withUnsafeBytes(for:_:)``
/// immediately and records a copy of the resulting buffer instead. If
/// `attachableValue` throws an error when the testing library calls its
/// ``Attachable/withUnsafeBytes(for:_:)`` function, the testing library
/// records that error as an issue in the current test.
///
/// @Metadata {
/// @Available(Swift, introduced: 6.2)
Expand All @@ -332,18 +345,18 @@ extension Attachment where AttachableValue: ~Copyable {
///
/// - Parameters:
/// - attachableValue: The value to attach.
/// - preferredName: The preferred name of the attachment when writing it to
/// a test report or to disk. If `nil`, the testing library attempts to
/// derive a reasonable filename for the attached value.
/// - preferredName: The preferred name of the attachment to use when saving
/// it. If `nil`, the testing library attempts to generate a reasonable
/// filename for the attached value.
/// - sourceLocation: The source location of the call to this function.
///
/// When `attachableValue` is an instance of a type that does not conform to
/// the [`Sendable`](https://developer.apple.com/documentation/swift/sendable)
/// protocol, the testing library encodes it as data immediately. If
/// `attachableValue` throws an error when the testing library attempts to
/// encode it, the testing library records that error as an issue in the
/// current test and does not write the attachment to the test report or to
/// persistent storage.
/// protocol, the testing library calls its ``Attachable/withUnsafeBytes(for:_:)``
/// immediately and records a copy of the resulting buffer instead. If
/// `attachableValue` throws an error when the testing library calls its
/// ``Attachable/withUnsafeBytes(for:_:)`` function, the testing library
/// records that error as an issue in the current test.
///
/// This function creates a new instance of ``Attachment`` and immediately
/// attaches it to the current test.
Expand Down Expand Up @@ -372,10 +385,9 @@ extension Attachment where AttachableValue: ~Copyable {
/// - Throws: Whatever is thrown by `body`, or any error that prevented the
/// creation of the buffer.
///
/// The testing library uses this function when writing an attachment to a
/// test report or to a file on disk. This function calls the
/// ``Attachable/withUnsafeBytes(for:_:)`` function on this attachment's
/// ``attachableValue-2tnj5`` property.
/// The testing library uses this function when saving an attachment. This
/// function calls the ``Attachable/withUnsafeBytes(for:_:)`` function on this
/// attachment's ``attachableValue-2tnj5`` property.
///
/// @Metadata {
/// @Available(Swift, introduced: 6.2)
Expand Down Expand Up @@ -404,16 +416,16 @@ extension Attachment where AttachableValue: ~Copyable {
/// is derived from the value of the ``Attachment/preferredName`` property.
///
/// If you pass `--attachments-path` to `swift test`, the testing library
/// automatically uses this function to persist attachments to the directory
/// you specify.
/// automatically uses this function to save attachments to the directory you
/// specify.
///
/// This function does not get or set the value of the attachment's
/// ``fileSystemPath`` property. The caller is responsible for setting the
/// value of this property if needed.
///
/// This function is provided as a convenience to allow tools authors to write
/// attachments to persistent storage the same way that Swift Package Manager
/// does. You are not required to use this function.
/// This function is provided as a convenience to allow tools authors to save
/// attachments the same way that Swift Package Manager does. You are not
/// required to use this function.
@_spi(ForToolsIntegrationOnly)
public borrowing func write(toFileInDirectoryAtPath directoryPath: String) throws -> String {
try write(
Expand Down Expand Up @@ -505,9 +517,9 @@ extension Configuration {
/// - Returns: Whether or not to continue handling the event.
///
/// This function is called automatically by ``handleEvent(_:in:)``. You do
/// not need to call it elsewhere. It automatically persists the attachment
/// not need to call it elsewhere. It automatically saves the attachment
/// associated with `event` and modifies `event` to include the path where the
/// attachment was stored.
/// attachment was saved.
func handleValueAttachedEvent(_ event: inout Event, in eventContext: borrowing Event.Context) -> Bool {
guard let attachmentsPath else {
// If there is no path to which attachments should be written, there's
Expand All @@ -519,9 +531,9 @@ extension Configuration {
preconditionFailure("Passed the wrong kind of event to \(#function) (expected valueAttached, got \(event.kind)). Please file a bug report at https://github.com/swiftlang/swift-testing/issues/new")
}
if attachment.fileSystemPath != nil {
// Somebody already persisted this attachment. This isn't necessarily a
// logic error in the testing library, but it probably means we shouldn't
// persist it again. Suppress the event.
// Somebody already saved this attachment. This isn't necessarily a logic
// error in the testing library, but it probably means we shouldn't save
// it again. Suppress the event.
return false
}

Expand Down
1 change: 1 addition & 0 deletions Sources/Testing/CMakeLists.txt
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Expand Up @@ -98,6 +98,7 @@ add_library(Testing
Test+Discovery.swift
Test+Discovery+Legacy.swift
Test+Macro.swift
Traits/AttachmentSavingTrait.swift
Traits/Bug.swift
Traits/Comment.swift
Traits/Comment+Macro.swift
Expand Down
8 changes: 8 additions & 0 deletions Sources/Testing/Events/Event.swift
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Expand Up @@ -191,6 +191,14 @@ public struct Event: Sendable {
/// The instant at which the event occurred.
public var instant: Test.Clock.Instant

/// Whether or not this event was deferred.
///
/// A deferred event is handled significantly later than when was posted.
///
/// We currently use this property in our tests, but do not expose it as API
/// or SPI. We can expose it in the future if tools need it.
var wasDeferred: Bool = false

/// Initialize an instance of this type.
///
/// - Parameters:
Expand Down
12 changes: 0 additions & 12 deletions Sources/Testing/Running/Configuration+EventHandling.swift
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Expand Up @@ -23,18 +23,6 @@ extension Configuration {
var contextCopy = copy context
contextCopy.configuration = self
contextCopy.configuration?.eventHandler = { _, _ in }

#if !SWT_NO_FILE_IO
if case .valueAttached = event.kind {
var eventCopy = copy event
guard handleValueAttachedEvent(&eventCopy, in: contextCopy) else {
// The attachment could not be handled, so suppress this event.
return
}
return eventHandler(eventCopy, contextCopy)
}
#endif

return eventHandler(event, contextCopy)
}
}
Expand Down
14 changes: 12 additions & 2 deletions Sources/Testing/Running/Runner.RuntimeState.swift
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Expand Up @@ -47,9 +47,19 @@ extension Runner {
return
}

configuration.eventHandler = { [eventHandler = configuration.eventHandler] event, context in
configuration.eventHandler = { [oldEventHandler = configuration.eventHandler] event, context in
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This code isn't new, but needed to move from handleEvent as it imposed the wrong layering (saving the attachment before any event handlers actually ran.)

#if !SWT_NO_FILE_IO
var event = copy event
if case .valueAttached = event.kind {
guard let configuration = context.configuration,
configuration.handleValueAttachedEvent(&event, in: context) else {
// The attachment could not be handled, so suppress this event.
return
}
}
#endif
RuntimeState.$current.withValue(existingRuntimeState) {
eventHandler(event, context)
oldEventHandler(event, context)
}
}
}
Expand Down
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