Use built-in swift-testing for Xcode 16

[417-72KI]

No description provided.

[Copilot]

Pull Request Overview

This PR updates the project to use the built-in swift-testing framework available in Swift 6.0 (Xcode 16) while maintaining backward compatibility with earlier compiler versions. The changes add thread safety to shared state and enable test serialization for the new testing framework.

• Conditionally uses built-in swift-testing for Swift 6.0+ and falls back to the external package for earlier versions
• Adds thread-safe access to the stub registry using NSLock
• Enables serialized test execution for Swift 6.0+ to prevent race conditions

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
Package.swift	Conditionally includes swift-testing package dependency only for compiler versions < 6.0
StubNetworkKitTests_SwiftTesting.swift	Adds .serialized trait to test suite for Swift 6.0+ to ensure sequential test execution
StubURLProtocol.swift	Introduces NSLock to synchronize access to shared stubs array
TestPlan.xctestplan	Removes repeatInNewRunnerProcess option from test configuration

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[Copilot]

Build-time conditional compilation directives like #if compiler(<6.0) are evaluated during package manifest compilation, not during target compilation. This means the condition will be checked against the Swift compiler version used to build the Package.swift file itself, not the version used to build the targets. This will not achieve the intended backward compatibility. Consider using target-level conditions or separate package manifests for different Swift versions instead.

Suggested change

	#if compiler(<6.0)
	package.dependencies.append(contentsOf: [
	.package(url: "https://github.com/apple/swift-testing", exact: "0.3.0"),
	])
	testTarget.dependencies.append(contentsOf: [
	.product(name: "Testing", package: "swift-testing"),
	])
	#endif
	// NOTE: Conditional compilation directives like `#if compiler(<6.0)` are evaluated during manifest compilation,
	// not during target compilation. To support Swift < 6.0, consider using separate manifests or document this requirement.
	// If you need to add the swift-testing dependency only for Swift < 6.0, update the manifest manually as needed.

[Copilot]

Pull Request Overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

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[Copilot]

OSAllocatedUnfairLock is only available on macOS 13.0+, iOS 16.0+, watchOS 9.0+, and tvOS 16.0+. While this aligns with the package's minimum platform versions in Package.swift, the lack of an explicit @available annotation makes the platform requirements less clear and could cause issues if the minimum platform versions are lowered in the future. Consider adding an @available annotation to make the dependency explicit.

Suggested change

	final class StubURLProtocol: URLProtocol {
	final class StubURLProtocol: URLProtocol {
	@available(macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0, *)

[Copilot]

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

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Lock is only defined when either os or Synchronization can be imported. In the repo’s CI there is a Linux test job (Swift 5.10–6.2), where canImport(os) is false and Synchronization may not be available (e.g., Swift 5.10), leaving no Lock type and breaking the build. Add a cross-platform fallback implementation (e.g., NSLock/pthread_mutex/DispatchSemaphore) under an #else branch so the module compiles on Linux.

[Copilot]

The withLock wrapper constrains the return type to R: Sendable, which is stricter than the underlying lock APIs and can make this utility unusable for non-Sendable intermediate values inside the module. Unless you specifically need this constraint, consider removing it to keep Lock generally usable.

Suggested change

	func withLock<R: Sendable>(_ body: @Sendable (inout State) throws -> R) rethrows -> R {
	func withLock<R>(_ body: @Sendable (inout State) throws -> R) rethrows -> R {