[SWT-NNNN] Attachments

Test authors frequently need to include out-of-band data with tests that can be
used to diagnose issues when a test fails. This proposal introduces a new API
called "attachments" (analogous to the same-named feature in XCTest) as well as
the infrastructure necessary to create new attachments and handle them in tools
like VS Code.

Read the full proposal [here]().

Author: grynspan

Documentation/ABI/JSON.md

@@ -188,19 +188,24 @@ sufficient information to display the event in a human-readable format.
   "kind": <event-kind>,
   "instant": <instant>, ; when the event occurred
   ["issue": <issue>,] ; the recorded issue (if "kind" is "issueRecorded")
+  ["attachment": <attachment>,] ; the attachment (if kind is "valueAttached")
   "messages": <array:message>,
   ["testID": <test-id>,]
 }
 
 <event-kind> ::= "runStarted" | "testStarted" | "testCaseStarted" |
   "issueRecorded" | "testCaseEnded" | "testEnded" | "testSkipped" |
-  "runEnded" ; additional event kinds may be added in the future
+  "runEnded" | "valueAttached"; additional event kinds may be added in the future
 
 <issue> ::= {
   "isKnown": <bool>, ; is this a known issue or not?
   ["sourceLocation": <source-location>,] ; where the issue occurred, if known
 }
 
+<attachment> ::= {
+  "path": <string>, ; the absolute path to the attachment on disk
+}
+
 <message> ::= {
   "symbol": <message-symbol>,
   "text": <string>, ; the human-readable text of this message

Documentation/Proposals/NNNN-attachments.md

@@ -9,7 +9,7 @@
 //
 
 #if canImport(Foundation)
-@_spi(Experimental) public import Testing
+public import Testing
 public import Foundation
 
 // This implementation is necessary to let the compiler disambiguate when a type
@@ -18,7 +18,9 @@ public import Foundation
 // (which explicitly document what happens when a type conforms to both
 // protocols.)
 
-@_spi(Experimental)
+/// @Metadata {
+///   @Available(Swift, introduced: 6.2)
+/// }
 extension Attachable where Self: Encodable & NSSecureCoding {
   @_documentation(visibility: private)
   public func withUnsafeBytes<R>(for attachment: borrowing Attachment<Self>, _ body: (UnsafeRawBufferPointer) throws -> R) throws -> R {

Sources/Overlays/_Testing_Foundation/Attachments/Attachable+Encodable+NSSecureCoding.swift

@@ -9,7 +9,7 @@
 //
 
 #if canImport(Foundation)
-@_spi(Experimental) public import Testing
+public import Testing
 private import Foundation
 
 /// A common implementation of ``withUnsafeBytes(for:_:)`` that is used when a
@@ -53,7 +53,10 @@ func withUnsafeBytes<E, R>(encoding attachableValue: borrowing E, for attachment
 // Implement the protocol requirements generically for any encodable value by
 // encoding to JSON. This lets developers provide trivial conformance to the
 // protocol for types that already support Codable.
-@_spi(Experimental)
+
+/// @Metadata {
+///   @Available(Swift, introduced: 6.2)
+/// }
 extension Attachable where Self: Encodable {
   /// Encode this value into a buffer using either [`PropertyListEncoder`](https://developer.apple.com/documentation/foundation/propertylistencoder)
   /// or [`JSONEncoder`](https://developer.apple.com/documentation/foundation/jsonencoder),
@@ -86,6 +89,10 @@ extension Attachable where Self: Encodable {
   /// _and_ [`NSSecureCoding`](https://developer.apple.com/documentation/foundation/nssecurecoding),
   /// the default implementation of this function uses the value's conformance
   /// to `Encodable`.
+  ///
+  /// @Metadata {
+  ///   @Available(Swift, introduced: 6.2)
+  /// }
   public func withUnsafeBytes<R>(for attachment: borrowing Attachment<Self>, _ body: (UnsafeRawBufferPointer) throws -> R) throws -> R {
     try _Testing_Foundation.withUnsafeBytes(encoding: self, for: attachment, body)
   }

Sources/Overlays/_Testing_Foundation/Attachments/Attachable+Encodable.swift

@@ -9,13 +9,16 @@
 //
 
 #if canImport(Foundation)
-@_spi(Experimental) public import Testing
+public import Testing
 public import Foundation
 
 // As with Encodable, implement the protocol requirements for
 // NSSecureCoding-conformant classes by default. The implementation uses
 // NSKeyedArchiver for encoding.
-@_spi(Experimental)
+
+/// @Metadata {
+///   @Available(Swift, introduced: 6.2)
+/// }
 extension Attachable where Self: NSSecureCoding {
   /// Encode this object using [`NSKeyedArchiver`](https://developer.apple.com/documentation/foundation/nskeyedarchiver)
   /// into a buffer, then call a function and pass that buffer to it.
@@ -46,6 +49,10 @@ extension Attachable where Self: NSSecureCoding {
   /// _and_ [`NSSecureCoding`](https://developer.apple.com/documentation/foundation/nssecurecoding),
   /// the default implementation of this function uses the value's conformance
   /// to `Encodable`.
+  ///
+  /// @Metadata {
+  ///   @Available(Swift, introduced: 6.2)
+  /// }
   public func withUnsafeBytes<R>(for attachment: borrowing Attachment<Self>, _ body: (UnsafeRawBufferPointer) throws -> R) throws -> R {
     let format = try EncodingFormat(for: attachment)
 

Sources/Overlays/_Testing_Foundation/Attachments/Attachable+NSSecureCoding.swift

@@ -9,7 +9,7 @@
 //
 
 #if canImport(Foundation)
-@_spi(Experimental) public import Testing
+public import Testing
 public import Foundation
 
 #if !SWT_NO_PROCESS_SPAWNING && os(Windows)
@@ -32,7 +32,6 @@ extension URL {
   }
 }
 
-@_spi(Experimental)
 extension Attachment where AttachableValue == _AttachableURLContainer {
 #if SWT_TARGET_OS_APPLE
   /// An operation queue to use for asynchronously reading data from disk.
@@ -51,6 +50,10 @@ extension Attachment where AttachableValue == _AttachableURLContainer {
   ///     attachment.
   ///
   /// - Throws: Any error that occurs attempting to read from `url`.
+  ///
+  /// @Metadata {
+  ///   @Available(Swift, introduced: 6.2)
+  /// }
   public init(
     contentsOf url: URL,
     named preferredName: String? = nil,

Sources/Overlays/_Testing_Foundation/Attachments/Attachment+URL.swift

@@ -9,11 +9,16 @@
 //
 
 #if canImport(Foundation)
-@_spi(Experimental) public import Testing
+public import Testing
 public import Foundation
 
-@_spi(Experimental)
+/// @Metadata {
+///   @Available(Swift, introduced: 6.2)
+/// }
 extension Data: Attachable {
+  /// @Metadata {
+  ///   @Available(Swift, introduced: 6.2)
+  /// }
   public func withUnsafeBytes<R>(for attachment: borrowing Attachment<Self>, _ body: (UnsafeRawBufferPointer) throws -> R) throws -> R {
     try withUnsafeBytes(body)
   }

Sources/Overlays/_Testing_Foundation/Attachments/Data+Attachable.swift

@@ -9,7 +9,7 @@
 //
 
 #if canImport(Foundation)
-@_spi(Experimental) import Testing
+import Testing
 import Foundation
 
 /// An enumeration describing the encoding formats we support for `Encodable`

Sources/Overlays/_Testing_Foundation/Attachments/EncodingFormat.swift

@@ -9,15 +9,14 @@
 //
 
 #if canImport(Foundation)
-@_spi(Experimental) public import Testing
+public import Testing
 public import Foundation
 
 /// A wrapper type representing file system objects and URLs that can be
 /// attached indirectly.
 ///
 /// You do not need to use this type directly. Instead, initialize an instance
 /// of ``Attachment`` using a file URL.
-@_spi(Experimental)
 public struct _AttachableURLContainer: Sendable {
   /// The underlying URL.
   var url: URL

Sources/Overlays/_Testing_Foundation/Attachments/_AttachableURLContainer.swift

@@ -27,7 +27,7 @@ extension ABI {
       case testStarted
       case testCaseStarted
       case issueRecorded
-      case valueAttached = "_valueAttached"
+      case valueAttached
       case testCaseEnded
       case testEnded
       case testSkipped
@@ -50,9 +50,7 @@ extension ABI {
     ///
     /// The value of this property is `nil` unless the value of the
     /// ``kind-swift.property`` property is ``Kind-swift.enum/valueAttached``.
-    ///
-    /// - Warning: Attachments are not yet part of the JSON schema.
-    var _attachment: EncodedAttachment<V>?
+    var attachment: EncodedAttachment<V>?
 
     /// Human-readable messages associated with this event that can be presented
     /// to the user.
@@ -82,7 +80,7 @@ extension ABI {
         issue = EncodedIssue(encoding: recordedIssue, in: eventContext)
       case let .valueAttached(attachment):
         kind = .valueAttached
-        _attachment = EncodedAttachment(encoding: attachment, in: eventContext)
+        self.attachment = EncodedAttachment(encoding: attachment, in: eventContext)
       case .testCaseEnded:
         if eventContext.test?.isParameterized == false {
           return nil