CoreTransferable attachments

Package.swift

@@ -154,6 +154,7 @@ let package = Package(
         "_Testing_AppKit",
         "_Testing_CoreGraphics",
         "_Testing_CoreImage",
+        "_Testing_CoreTransferable",
         "_Testing_Foundation",
         "_Testing_UIKit",
         "_Testing_WinSDK",
@@ -256,6 +257,15 @@ let package = Package(
       exclude: ["CMakeLists.txt"],
       swiftSettings: .packageSettings() + .enableLibraryEvolution() + .moduleABIName("_Testing_CoreImage")
     ),
+    .target(
+      name: "_Testing_CoreTransferable",
+      dependencies: [
+        "Testing",
+      ],
+      path: "Sources/Overlays/_Testing_CoreTransferable",
+      exclude: ["CMakeLists.txt"],
+      swiftSettings: .packageSettings() + .enableLibraryEvolution() + .moduleABIName("_Testing_CoreTransferable")
+    ),
     .target(
       name: "_Testing_Foundation",
       dependencies: [
@@ -399,6 +409,7 @@ extension Array where Element == PackageDescription.SwiftSetting {
       .enableExperimentalFeature("AvailabilityMacro=_uttypesAPI:macOS 11.0, iOS 14.0, watchOS 7.0, tvOS 14.0"),
       .enableExperimentalFeature("AvailabilityMacro=_clockAPI:macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0"),
       .enableExperimentalFeature("AvailabilityMacro=_typedThrowsAPI:macOS 15.0, iOS 18.0, watchOS 11.0, tvOS 18.0, visionOS 2.0"),
+      .enableExperimentalFeature("AvailabilityMacro=_transferableAPI:macOS 15.2, iOS 18.2, watchOS 11.2, tvOS 18.2, visionOS 2.2"),
       .enableExperimentalFeature("AvailabilityMacro=_castingWithNonCopyableGenerics:macOS 15.0, iOS 18.0, watchOS 11.0, tvOS 18.0, visionOS 2.0"),
 
       .enableExperimentalFeature("AvailabilityMacro=_distantFuture:macOS 99.0, iOS 99.0, watchOS 99.0, tvOS 99.0, visionOS 99.0"),

Sources/Overlays/CMakeLists.txt

@@ -9,6 +9,7 @@
 add_subdirectory(_Testing_AppKit)
 add_subdirectory(_Testing_CoreGraphics)
 add_subdirectory(_Testing_CoreImage)
+add_subdirectory(_Testing_CoreTransferable)
 add_subdirectory(_Testing_Foundation)
 add_subdirectory(_Testing_UIKit)
 add_subdirectory(_Testing_WinSDK)

Sources/Overlays/_Testing_CoreTransferable/Attachments/Attachment+Transferable.swift

@@ -0,0 +1,87 @@
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2026 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for Swift project authors
+//
+
+#if canImport(CoreTransferable)
+public import Testing
+public import CoreTransferable
+
+public import UniformTypeIdentifiers
+
+/// @Metadata {
+///   @Available(Swift, introduced: 6.4)
+/// }
+@available(_transferableAPI, *)
+extension Attachment {
+  /// Initialize an instance of this type that encloses the given transferable
+  /// value.
+  ///
+  /// - Parameters:
+  ///   - transferableValue: The value that will be attached to the output of
+  ///     the test run.
+  ///   - contentType: The content type with which to export `transferableValue`.
+  ///     If this argument is `nil`, the testing library calls [`exportedContentTypes(_:)`](https://developer.apple.com/documentation/coretransferable/transferable/exportedcontenttypes(_:))
+  ///     on `transferableValue` and uses the first type the function returns
+  ///     that conforms to [`UTType.data`](https://developer.apple.com/documentation/uniformtypeidentifiers/uttype-swift.struct/data).
+  ///   - 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.
+  ///
+  /// - Throws: Any error that occurs while exporting `transferableValue`.
+  ///
+  /// Use this initializer to create an instance of ``Attachment`` from a value
+  /// that conforms to the [`Transferable`](https://developer.apple.com/documentation/coretransferable/transferable)
+  /// protocol.
+  ///
+  /// ```swift
+  /// let menu = FoodTruck.menu
+  /// let attachment = try await Attachment(exporting: menu, as: .pdf)
+  /// Attachment.record(attachment)
+  /// ```
+  ///
+  /// When you call this initializer and pass it a transferable value, it
+  /// calls [`exported(as:)`](https://developer.apple.com/documentation/coretransferable/transferable/exported(as:))
+  /// on that value. This operation may take some time, so this initializer
+  /// suspends the calling task until it is complete.
+  ///
+  /// @Metadata {
+  ///   @Available(Swift, introduced: 6.4)
+  /// }
+  public init<T>(
+    exporting transferableValue: T,
+    as contentType: UTType? = nil,
+    named preferredName: String? = nil,
+    sourceLocation: SourceLocation = #_sourceLocation
+  ) async throws where T: Transferable, AttachableValue == _AttachableTransferableWrapper<T> {
+    let transferableWrapper = try await _AttachableTransferableWrapper(exporting: transferableValue, as: contentType)
+    self.init(transferableWrapper, named: preferredName, sourceLocation: sourceLocation)
+  }
+}
+
+// MARK: -
+
+/// A type describing errors that can occur when attaching a transferable value.
+enum TransferableAttachmentError: Error {
+  /// The developer did not pass a content type and the value did not list any
+  /// that conform to `UTType.data`.
+  case suitableContentTypeNotFound
+}
+
+extension TransferableAttachmentError: CustomStringConvertible {
+  var description: String {
+    switch self {
+    case .suitableContentTypeNotFound:
+      "The value does not list any exported content types that conform to 'UTType.data'."
+    }
+  }
+}
+#endif

Sources/Overlays/_Testing_CoreTransferable/Attachments/_AttachableTransferableWrapper.swift

@@ -0,0 +1,81 @@
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2026 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for Swift project authors
+//
+
+#if canImport(CoreTransferable)
+public import Testing
+public import CoreTransferable
+
+private import Foundation
+import UniformTypeIdentifiers
+
+/// A wrapper type representing transferable values that can be attached
+/// indirectly.
+///
+/// You do not need to use this type directly. Instead, initialize an instance
+/// of ``Attachment`` using an instance of a type conforming to the [`Transferable`](https://developer.apple.com/documentation/coretransferable/transferable)
+/// protocol.
+///
+/// @Metadata {
+///   @Available(Swift, introduced: 6.4)
+/// }
+@available(_transferableAPI, *)
+public struct _AttachableTransferableWrapper<T>: Sendable where T: Transferable {
+  /// The transferable value.
+  private var _transferableValue: T
+
+  /// The content type used to export the transferable value.
+  private var _contentType: UTType
+
+  /// The exported form of the transferable value.
+  private var _bytes: Data
+
+  init(exporting transferableValue: T, as contentType: UTType?) async throws {
+    let contentType = contentType ?? transferableValue.exportedContentTypes()
+      .first { $0.conforms(to: .data) }
+    guard let contentType else {
+      throw TransferableAttachmentError.suitableContentTypeNotFound
+    }
+
+    _transferableValue = transferableValue
+    _contentType = contentType
+    _bytes = try await transferableValue.exported(as: contentType)
+  }
+}
+
+// MARK: -
+
+/// @Metadata {
+///   @Available(Swift, introduced: 6.4)
+/// }
+@available(_transferableAPI, *)
+extension _AttachableTransferableWrapper: AttachableWrapper {
+  /// @Metadata {
+  ///   @Available(Swift, introduced: 6.4)
+  /// }
+  public var wrappedValue: T {
+    _transferableValue
+  }
+
+  /// @Metadata {
+  ///   @Available(Swift, introduced: 6.4)
+  /// }
+  public func withUnsafeBytes<R>(for attachment: borrowing Attachment<Self>, _ body: (UnsafeRawBufferPointer) throws -> R) throws -> R {
+    try _bytes.withUnsafeBytes(body)
+  }
+
+  /// @Metadata {
+  ///   @Available(Swift, introduced: 6.4)
+  /// }
+  public borrowing func preferredName(for attachment: borrowing Attachment<Self>, basedOn suggestedName: String) -> String {
+    let baseName = _transferableValue.suggestedFilename ?? suggestedName
+    return (baseName as NSString).appendingPathExtension(for: _contentType)
+  }
+}
+#endif

Sources/Overlays/_Testing_CoreTransferable/CMakeLists.txt

@@ -0,0 +1,24 @@
+# This source file is part of the Swift.org open source project
+#
+# Copyright (c) 2026 Apple Inc. and the Swift project authors
+# Licensed under Apache License v2.0 with Runtime Library Exception
+#
+# See https://swift.org/LICENSE.txt for license information
+# See https://swift.org/CONTRIBUTORS.txt for Swift project authors
+
+if (CMAKE_SYSTEM_NAME STREQUAL "Darwin")
+  include(ModuleABIName)
+  add_library(_Testing_CoreTransferable
+    Attachments/_AttachableTransferableWrapper.swift
+    Attachments/Attachment+Transferable.swift
+    ReexportTesting.swift)
+
+  target_link_libraries(_Testing_CoreTransferable PUBLIC
+    Testing)
+
+  target_compile_options(_Testing_CoreTransferable PRIVATE
+    -enable-library-evolution
+    -emit-module-interface -emit-module-interface-path $<TARGET_PROPERTY:_Testing_CoreTransferable,Swift_MODULE_DIRECTORY>/_Testing_CoreTransferable.swiftinterface)
+
+  _swift_testing_install_target(_Testing_CoreTransferable)
+endif()

Sources/Overlays/_Testing_CoreTransferable/ReexportTesting.swift

@@ -0,0 +1,11 @@
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2026 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for Swift project authors
+//
+
+@_exported public import Testing

Sources/Testing/Testing.swiftcrossimport/CoreTransferable.swiftoverlay

@@ -0,0 +1,3 @@
+version: 1
+modules:
+- name: _Testing_CoreTransferable

Tests/TestingTests/AttachmentTests.swift

@@ -26,6 +26,10 @@ import CoreGraphics
 import CoreImage
 import _Testing_CoreImage
 #endif
+#if canImport(CoreTransferable) && canImport(_Testing_CoreTransferable)
+import CoreTransferable
+@_spi(Experimental) import _Testing_CoreTransferable
+#endif
 #if canImport(UIKit) && canImport(_Testing_UIKit)
 import UIKit
 import _Testing_UIKit
@@ -258,7 +262,7 @@ struct AttachmentTests {
 
         #expect((attachment.attachableValue as Any) is AnyAttachable.Wrapped)
         #expect(attachment.sourceLocation.fileID == #fileID)
-       valueAttached()
+        valueAttached()
       }
 
       await Test {
@@ -486,6 +490,45 @@ struct AttachmentTests {
     }
   }
 #endif
+
+#if canImport(CoreTransferable) && canImport(_Testing_CoreTransferable)
+  @available(_transferableAPI, *)
+  @Test("Attach Transferable-conformant value")
+  func transferable() async throws {
+    let value = MyTransferable()
+    let attachment = try await Attachment(exporting: value, as: .plainText)
+    #expect(value == attachment.attachableValue)
+    try attachment.withUnsafeBytes { bytes in
+      #expect(Array(bytes) == Array(MyTransferable.stringValue.utf8))
+    }
+  }
+
+  @available(_transferableAPI, *)
+  @Test("Attach Transferable-conformant value with a nonsensical type")
+  func transferableWithNonsensicalType() async throws {
+    let value = MyTransferable()
+    await #expect(throws: (any Error).self) {
+      _ = try await Attachment(exporting: value, as: .gif)
+    }
+  }
+
+  @available(_transferableAPI, *)
+  @Test("Preferred name of Transferable-conformant value")
+  func transferablePreferredName() async throws {
+    let value = MyTransferable()
+    let attachment = try await Attachment(exporting: value)
+    #expect(attachment.preferredName == "untitled.txt")
+  }
+
+  @available(_transferableAPI, *)
+  @Test("Attach Transferable-conformant value with no available type")
+  func transferableWithNoAvailableType() async throws {
+    let value = MyBadTransferable()
+    await #expect(throws: (any Error).self) {
+      _ = try await Attachment(exporting: value)
+    }
+  }
+#endif
 }
 
 extension AttachmentTests {
@@ -1083,6 +1126,26 @@ struct MySendableAttachableWithDefaultByteCount: Attachable, Sendable {
   }
 }
 
+#if canImport(CoreTransferable) && canImport(_Testing_CoreTransferable)
+struct MyTransferable: Transferable, Equatable {
+  static let stringValue = "This isn't even my exported form!"
+
+  static var transferRepresentation: some TransferRepresentation {
+    DataRepresentation(exportedContentType: .plainText) { instance in
+      Data(Self.stringValue.utf8)
+    }
+  }
+}
+
+struct MyBadTransferable: Transferable, Equatable {
+  static var transferRepresentation: some TransferRepresentation {
+    DataRepresentation(exportedContentType: .directory) { _ in
+      throw MyError()
+    }
+  }
+}
+#endif
+
 #if canImport(Foundation) && canImport(_Testing_Foundation)
 struct MyCodableAttachable: Codable, Attachable, Sendable {
   var string: String

cmake/modules/shared/AvailabilityDefinitions.cmake

@@ -13,5 +13,6 @@ add_compile_options(
   "SHELL:$<$<COMPILE_LANGUAGE:Swift>:-Xfrontend -define-availability -Xfrontend \"_uttypesAPI:macOS 11.0, iOS 14.0, watchOS 7.0, tvOS 14.0\">"
   "SHELL:$<$<COMPILE_LANGUAGE:Swift>:-Xfrontend -define-availability -Xfrontend \"_clockAPI:macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0\">"
   "SHELL:$<$<COMPILE_LANGUAGE:Swift>:-Xfrontend -define-availability -Xfrontend \"_typedThrowsAPI:macOS 15.0, iOS 18.0, watchOS 11.0, tvOS 18.0, visionOS 2.0\">"
+  "SHELL:$<$<COMPILE_LANGUAGE:Swift>:-Xfrontend -define-availability -Xfrontend \"_transferableAPI:macOS 15.2, iOS 18.2, watchOS 11.2, tvOS 18.2, visionOS 2.2\">"
   "SHELL:$<$<COMPILE_LANGUAGE:Swift>:-Xfrontend -define-availability -Xfrontend \"_castingWithNonCopyableGenerics:macOS 15.0, iOS 18.0, watchOS 11.0, tvOS 18.0, visionOS 2.0\">"
   "SHELL:$<$<COMPILE_LANGUAGE:Swift>:-Xfrontend -define-availability -Xfrontend \"_distantFuture:macOS 99.0, iOS 99.0, watchOS 99.0, tvOS 99.0, visionOS 99.0\">")