[6.0] Update package templates to use Swift Testing in the toolchain rather than as a package dependency.

Fixtures/Miscellaneous/TestDiscovery/SwiftTesting/Package.swift

@@ -1,18 +1,9 @@
-// swift-tools-version: 5.10
+// swift-tools-version: 6.0
 import PackageDescription
 
 let package = Package(
     name: "SwiftTesting",
-    platforms: [
-      .macOS(.v13), .iOS(.v16), .watchOS(.v9), .tvOS(.v16), .visionOS(.v1)
-    ],
-    dependencies: [
-      .package(url: "https://github.com/apple/swift-testing.git", branch: "main"),
-    ],
     targets: [
-        .testTarget(
-            name: "SwiftTestingTests",
-            dependencies: [.product(name: "Testing", package: "swift-testing"),]
-        ),
+        .testTarget(name: "SwiftTestingTests"),
     ]
 )

Sources/Commands/PackageCommands/Init.swift

@@ -56,14 +56,16 @@ extension SwiftPackageCommand {
 
             let packageName = self.packageName ?? cwd.basename
 
-            // Which testing libraries should be used? XCTest is on by default,
-            // but Swift Testing must remain off by default until it is present
-            // in the Swift toolchain.
+            // Testing is on by default, with XCTest only enabled explicitly.
+            // For macros this is reversed, since we don't support testing
+            // macros with Swift Testing yet.
             var supportedTestingLibraries = Set<BuildParameters.Testing.Library>()
-            if testLibraryOptions.isEnabled(.xctest) {
+            if testLibraryOptions.isExplicitlyEnabled(.xctest) ||
+                (initMode == .macro && testLibraryOptions.isEnabled(.xctest)) {
                 supportedTestingLibraries.insert(.xctest)
             }
-            if testLibraryOptions.isExplicitlyEnabled(.swiftTesting) {
+            if testLibraryOptions.isExplicitlyEnabled(.swiftTesting) ||
+                (initMode != .macro && testLibraryOptions.isEnabled(.swiftTesting)) {
                 supportedTestingLibraries.insert(.swiftTesting)
             }
 

Sources/PackageModelSyntax/AddTarget.swift

@@ -84,11 +84,6 @@ public struct AddTarget {
             // SwiftSyntax.
             target.dependencies.append(contentsOf: macroTargetDependencies)
 
-        case .test where configuration.testHarness == .swiftTesting:
-            // Testing targets using swift-testing need to depend on
-            // SwiftTesting from the swift-testing package.
-            target.dependencies.append(contentsOf: swiftTestingTestTargetDependencies)
-
         default:
             break;
         }
@@ -163,17 +158,6 @@ public struct AddTarget {
                 }
             }
 
-        case .test where configuration.testHarness == .swiftTesting:
-            if !manifest.description.contains("swift-testing") {
-                newPackageCall = try AddPackageDependency
-                    .addPackageDependencyLocal(
-                        .swiftTesting(
-                          configuration: installedSwiftPMConfiguration
-                        ),
-                        to: newPackageCall
-                    )
-            }
-
         default: break;
         }
 
@@ -212,8 +196,7 @@ public struct AddTarget {
                 importModuleNames.append("XCTest")
 
             case .swiftTesting: 
-                // Import is handled by the added dependency.
-                break
+                importModuleNames.append("Testing")
             }
         }
 
@@ -380,35 +363,3 @@ fileprivate extension PackageDependency {
         )
     }
 }
-
-/// The set of dependencies we need to introduce to a newly-created macro
-/// target.
-fileprivate let swiftTestingTestTargetDependencies: [TargetDescription.Dependency] = [
-    .product(name: "Testing", package: "swift-testing"),
-]
-
-
-/// The package dependency for swift-testing, for use in test files.
-fileprivate extension PackageDependency {
-    /// Source control URL for the swift-syntax package.
-    static var swiftTestingURL: SourceControlURL {
-        "https://github.com/apple/swift-testing.git"
-    }
-
-    /// Package dependency on the swift-testing package.
-    static func swiftTesting(
-      configuration: InstalledSwiftPMConfiguration
-    ) -> PackageDependency {
-        let swiftTestingVersionDefault =
-            configuration.swiftTestingVersionForTestTemplate
-        let swiftTestingVersion = Version(swiftTestingVersionDefault.description)!
-
-        return .sourceControl(
-            identity: PackageIdentity(url: swiftTestingURL),
-            nameForTargetDependencyResolutionOnly: nil,
-            location: .remote(swiftTestingURL),
-            requirement: .range(.upToNextMajor(from: swiftTestingVersion)),
-            productFilter: .everything
-        )
-    }
-}

Sources/SPMTestSupport/misc.swift

@@ -474,7 +474,7 @@ extension InitPackage {
     public convenience init(
         name: String,
         packageType: PackageType,
-        supportedTestingLibraries: Set<BuildParameters.Testing.Library> = [.xctest],
+        supportedTestingLibraries: Set<BuildParameters.Testing.Library> = [.swiftTesting],
         destinationPath: AbsolutePath,
         fileSystem: FileSystem
     ) throws {

Sources/Workspace/InitPackage.swift

@@ -36,7 +36,7 @@ public final class InitPackage {
 
         public init(
             packageType: PackageType,
-            supportedTestingLibraries: Set<BuildParameters.Testing.Library> = [.xctest],
+            supportedTestingLibraries: Set<BuildParameters.Testing.Library>,
             platforms: [SupportedPlatform] = []
         ) {
             self.packageType = packageType
@@ -186,8 +186,8 @@ public final class InitPackage {
 
             var platforms = options.platforms
 
-            // Macros and swift-testing require macOS 10.15, iOS 13, etc.
-            if packageType == .macro || options.supportedTestingLibraries.contains(.swiftTesting) {
+            // Macros require macOS 10.15, iOS 13, etc.
+            if packageType == .macro {
                 func addIfMissing(_ newPlatform: SupportedPlatform) {
                   if platforms.contains(where: { platform in
                       platform.platform == newPlatform.platform
@@ -275,9 +275,6 @@ public final class InitPackage {
             } else if packageType == .macro {
                 dependencies.append(#".package(url: "https://github.com/swiftlang/swift-syntax.git", from: "\#(self.installedSwiftPMConfiguration.swiftSyntaxVersionForMacroTemplate.description)")"#)
             }
-            if options.supportedTestingLibraries.contains(.swiftTesting) {
-                dependencies.append(#".package(url: "https://github.com/apple/swift-testing.git", from: "0.11.0")"#)
-            }
             if !dependencies.isEmpty {
                 let dependencies = dependencies.map { dependency in
                     "        \(dependency),"
@@ -384,17 +381,7 @@ public final class InitPackage {
                     """
                 } else {
                     let testTarget: String
-                    if options.supportedTestingLibraries.contains(.swiftTesting) {
-                        testTarget = """
-                                .testTarget(
-                                    name: "\(pkgname)Tests",
-                                    dependencies: [
-                                        "\(pkgname)",
-                                        .product(name: "Testing", package: "swift-testing"),
-                                    ]
-                                ),
-                        """
-                    } else if options.supportedTestingLibraries.contains(.xctest) {
+                    if !options.supportedTestingLibraries.isEmpty {
                         testTarget = """
                                 .testTarget(
                                     name: "\(pkgname)Tests",
@@ -687,6 +674,10 @@ public final class InitPackage {
     private func writeLibraryTestsFile(_ path: AbsolutePath) throws {
         var content = ""
 
+        // XCTest is only added if it was explicitly asked for, so add tests
+        // for it *and* Testing if it is enabled (or just XCTest if Testing
+        // is explicitly disabled).
+
         if options.supportedTestingLibraries.contains(.swiftTesting) {
             content += "import Testing\n"
         }
@@ -695,20 +686,18 @@ public final class InitPackage {
         }
         content += "@testable import \(moduleName)\n"
 
-        // Prefer swift-testing if specified, otherwise XCTest. If both are
-        // specified, the developer is free to write tests using both
-        // libraries, but we still only want to present a single library's
-        // example tests.
+
         if options.supportedTestingLibraries.contains(.swiftTesting) {
             content += """
 
-                @Test func example() throws {
-                    // swift-testing Documentation
-                    // https://swiftpackageindex.com/apple/swift-testing/main/documentation/testing
+                @Test func example() async throws {
+                    // Write your test here and use APIs like `#expect(...)` to check expected conditions.
                 }
 
                 """
-        } else if options.supportedTestingLibraries.contains(.xctest) {
+        }
+
+        if options.supportedTestingLibraries.contains(.xctest) {
             content += """
 
                 final class \(moduleName)Tests: XCTestCase {
@@ -761,13 +750,15 @@ public final class InitPackage {
 
             """##
 
-        // Prefer swift-testing if specified, otherwise XCTest. If both are
-        // specified, the developer is free to write tests using both
-        // libraries, but we still only want to present a single library's
-        // example tests.
+
+        // XCTest is only added if it was explicitly asked for, so add tests
+        // for it *and* Testing if it is enabled.
+
         if options.supportedTestingLibraries.contains(.swiftTesting) {
             // FIXME: https://github.com/swiftlang/swift-syntax/issues/2400
-        } else if options.supportedTestingLibraries.contains(.xctest) {
+        }
+
+        if options.supportedTestingLibraries.contains(.xctest) {
             content += ##"""
                 final class \##(moduleName)Tests: XCTestCase {
                     func testMacro() throws {

Tests/CommandsTests/TestCommandTests.swift

@@ -276,10 +276,28 @@ final class TestCommandTests: CommandsTestCase {
     }
 
     func testBasicSwiftTestingIntegration() async throws {
+#if !canImport(Testing)
         try XCTSkipUnless(
             nil != Environment.current["SWIFT_PM_SWIFT_TESTING_TESTS_ENABLED"],
             "Skipping \(#function) because swift-testing tests are not explicitly enabled"
         )
+#endif
+
+        try await fixture(name: "Miscellaneous/TestDiscovery/SwiftTesting") { fixturePath in
+            do {
+                let (stdout, _) = try await SwiftPM.Test.execute(["--enable-swift-testing", "--disable-xctest"], packagePath: fixturePath)
+                XCTAssertMatch(stdout, .contains(#"Test "SOME TEST FUNCTION" started"#))
+            }
+        }
+    }
+
+    func testBasicSwiftTestingIntegration_ExperimentalFlag() async throws {
+#if !canImport(Testing)
+        try XCTSkipUnless(
+            nil != Environment.current["SWIFT_PM_SWIFT_TESTING_TESTS_ENABLED"],
+            "Skipping \(#function) because swift-testing tests are not explicitly enabled"
+        )
+#endif
 
         try await fixture(name: "Miscellaneous/TestDiscovery/SwiftTesting") { fixturePath in
             do {

Tests/PackageModelSyntaxTests/ManifestEditTests.swift

@@ -575,14 +575,8 @@ class ManifestEditTests: XCTestCase {
             // swift-tools-version: 5.5
             let package = Package(
                 name: "packages",
-                dependencies: [
-                    .package(url: "https://github.com/apple/swift-testing.git", from: "0.8.0"),
-                ],
                 targets: [
-                    .testTarget(
-                        name: "MyTest",
-                        dependencies: [ .product(name: "Testing", package: "swift-testing") ]
-                    ),
+                    .testTarget(name: "MyTest"),
                 ]
             )
             """,
@@ -618,7 +612,7 @@ class ManifestEditTests: XCTestCase {
             let package = Package(
                 name: "packages",
                 dependencies: [
-                    .package(url: "https://github.com/apple/swift-testing.git", from: "0.8.0"),
+                    .package(url: "https://github.com/swiftlang/swift-example.git", from: "1.2.3"),
                 ],
                 targets: [
                     .testTarget(
@@ -632,20 +626,20 @@ class ManifestEditTests: XCTestCase {
             let package = Package(
                 name: "packages",
                 dependencies: [
-                    .package(url: "https://github.com/apple/swift-testing.git", from: "0.8.0"),
+                    .package(url: "https://github.com/swiftlang/swift-example.git", from: "1.2.3"),
                 ],
                 targets: [
                     .testTarget(
                         name: "MyTest",
                         dependencies: [
-                            .product(name: "Testing", package: "swift-testing"),
+                            .product(name: "SomethingOrOther", package: "swift-example"),
                         ]
                     ),
                 ]
             )
             """) { manifest in
             try AddTargetDependency.addTargetDependency(
-                .product(name: "Testing", package: "swift-testing"),
+                .product(name: "SomethingOrOther", package: "swift-example"),
                 targetName: "MyTest",
                 to: manifest
             )