Build one test product for both Swift Testing and XCTest (with Swift Testing enabled by default.) (#7766)

This PR refactors the previously-experimental Swift Testing support
logic so that only a single build product is produced when using both
XCTest and Swift Testing, and detection of Swift Testing usage is no
longer needed at compile time.

On macOS, Xcode 16 is responsible for hosting Swift Testing content, so
additional changes may be needed in Xcode to support this refactoring.
Such changes are beyond the purview of the Swift open source project.

Resolves rdar://120864035.

---------

Co-authored-by: Pavel Yaskevich <[email protected]>

Author: grynspan

Sources/Build/BuildManifest/LLBuildManifestBuilder.swift

@@ -112,9 +112,7 @@ public class LLBuildManifestBuilder {
             }
         }
 
-        if self.plan.destinationBuildParameters.testingParameters.library == .xctest {
-            try self.addTestDiscoveryGenerationCommand()
-        }
+        try self.addTestDiscoveryGenerationCommand()
         try self.addTestEntryPointGenerationCommand()
 
         // Create command for all products in the plan.
@@ -310,9 +308,7 @@ extension LLBuildManifestBuilder {
 
             let outputs = testEntryPointTarget.target.sources.paths
 
-            let mainFileName = TestEntryPointTool.mainFileName(
-                for: self.plan.destinationBuildParameters.testingParameters.library
-            )
+            let mainFileName = TestEntryPointTool.mainFileName
             guard let mainOutput = (outputs.first { $0.basename == mainFileName }) else {
                 throw InternalError("main output (\(mainFileName)) not found")
             }

Sources/Build/BuildPlan/BuildPlan+Product.swift

@@ -275,10 +275,8 @@ extension BuildPlan {
         }
 
         // Add derived test targets, if necessary
-        if buildParameters.testingParameters.testProductStyle.requiresAdditionalDerivedTestTargets {
-            if product.type == .test, let derivedTestTargets = derivedTestTargetsMap[product.id] {
-                staticTargets.append(contentsOf: derivedTestTargets)
-            }
+        if product.type == .test, let derivedTestTargets = derivedTestTargetsMap[product.id] {
+            staticTargets.append(contentsOf: derivedTestTargets)
         }
 
         return (linkLibraries, staticTargets, systemModules, libraryBinaryPaths, providedLibraries, availableTools)

Sources/Build/BuildPlan/BuildPlan+Test.swift

@@ -34,13 +34,12 @@ extension BuildPlan {
         _ fileSystem: FileSystem,
         _ observabilityScope: ObservabilityScope
     ) throws -> [(product: ResolvedProduct, discoveryTargetBuildDescription: SwiftModuleBuildDescription?, entryPointTargetBuildDescription: SwiftModuleBuildDescription)] {
-        guard destinationBuildParameters.testingParameters.testProductStyle.requiresAdditionalDerivedTestTargets,
-              case .entryPointExecutable(let explicitlyEnabledDiscovery, let explicitlySpecifiedPath) =
-                destinationBuildParameters.testingParameters.testProductStyle
-        else {
-            throw InternalError("makeTestManifestTargets should not be used for build plan which does not require additional derived test targets")
+        var explicitlyEnabledDiscovery = false
+        var explicitlySpecifiedPath: AbsolutePath?
+        if case let .entryPointExecutable(caseExplicitlyEnabledDiscovery, caseExplicitlySpecifiedPath) = destinationBuildParameters.testingParameters.testProductStyle {
+            explicitlyEnabledDiscovery = caseExplicitlyEnabledDiscovery
+            explicitlySpecifiedPath = caseExplicitlySpecifiedPath
         }
-
         let isEntryPointPathSpecifiedExplicitly = explicitlySpecifiedPath != nil
 
         var isDiscoveryEnabledRedundantly = explicitlyEnabledDiscovery && !isEntryPointPathSpecifiedExplicitly
@@ -116,7 +115,7 @@ extension BuildPlan {
                 resolvedTargetDependencies: [ResolvedModule.Dependency]
             ) throws -> SwiftModuleBuildDescription {
                 let entryPointDerivedDir = destinationBuildParameters.buildPath.appending(components: "\(testProduct.name).derived")
-                let entryPointMainFileName = TestEntryPointTool.mainFileName(for: destinationBuildParameters.testingParameters.library)
+                let entryPointMainFileName = TestEntryPointTool.mainFileName
                 let entryPointMainFile = entryPointDerivedDir.appending(component: entryPointMainFileName)
                 let entryPointSources = Sources(paths: [entryPointMainFile], root: entryPointDerivedDir)
 
@@ -153,18 +152,17 @@ extension BuildPlan {
             let swiftTargetDependencies: [Module.Dependency]
             let resolvedTargetDependencies: [ResolvedModule.Dependency]
 
-            switch destinationBuildParameters.testingParameters.library {
-            case .xctest:
+            if destinationBuildParameters.triple.isDarwin() {
+                discoveryTargets = nil
+                swiftTargetDependencies = []
+                resolvedTargetDependencies = []
+            } else {
                 discoveryTargets = try generateDiscoveryTargets()
                 swiftTargetDependencies = [.module(discoveryTargets!.target, conditions: [])]
                 resolvedTargetDependencies = [.module(discoveryTargets!.resolved, conditions: [])]
-            case .swiftTesting:
-                discoveryTargets = nil
-                swiftTargetDependencies = testProduct.modules.map { .module($0.underlying, conditions: []) }
-                resolvedTargetDependencies = testProduct.modules.map { .module($0, conditions: []) }
             }
 
-            if let entryPointResolvedTarget = testProduct.testEntryPointModule {
+            if !destinationBuildParameters.triple.isDarwin(), let entryPointResolvedTarget = testProduct.testEntryPointModule {
                 if isEntryPointPathSpecifiedExplicitly || explicitlyEnabledDiscovery {
                     if isEntryPointPathSpecifiedExplicitly {
                         // Allow using the explicitly-specified test entry point target, but still perform test discovery and thus declare a dependency on the discovery modules.

Sources/Build/BuildPlan/BuildPlan.swift

@@ -473,31 +473,29 @@ public class BuildPlan: SPMBuildCore.BuildPlan {
         }
 
         // Plan the derived test targets, if necessary.
-        if destinationBuildParameters.testingParameters.testProductStyle.requiresAdditionalDerivedTestTargets {
-            let derivedTestTargets = try Self.makeDerivedTestTargets(
-                testProducts: productMap.values.filter {
-                    $0.product.type == .test
-                },
-                destinationBuildParameters: destinationBuildParameters,
-                toolsBuildParameters: toolsBuildParameters,
-                shouldDisableSandbox: self.shouldDisableSandbox,
-                self.fileSystem,
-                self.observabilityScope
-            )
-            for item in derivedTestTargets {
-                var derivedTestTargets = [item.entryPointTargetBuildDescription.target]
-
-                targetMap[item.entryPointTargetBuildDescription.target.id] = .swift(
-                    item.entryPointTargetBuildDescription
-                )
+        let derivedTestTargets = try Self.makeDerivedTestTargets(
+            testProducts: productMap.values.filter {
+                $0.product.type == .test
+            },
+            destinationBuildParameters: destinationBuildParameters,
+            toolsBuildParameters: toolsBuildParameters,
+            shouldDisableSandbox: self.shouldDisableSandbox,
+            self.fileSystem,
+            self.observabilityScope
+        )
+        for item in derivedTestTargets {
+            var derivedTestTargets = [item.entryPointTargetBuildDescription.target]
 
-                if let discoveryTargetBuildDescription = item.discoveryTargetBuildDescription {
-                    targetMap[discoveryTargetBuildDescription.target.id] = .swift(discoveryTargetBuildDescription)
-                    derivedTestTargets.append(discoveryTargetBuildDescription.target)
-                }
+            targetMap[item.entryPointTargetBuildDescription.target.id] = .swift(
+                item.entryPointTargetBuildDescription
+            )
 
-                self.derivedTestTargetsMap[item.product.id] = derivedTestTargets
+            if let discoveryTargetBuildDescription = item.discoveryTargetBuildDescription {
+                targetMap[discoveryTargetBuildDescription.target.id] = .swift(discoveryTargetBuildDescription)
+                derivedTestTargets.append(discoveryTargetBuildDescription.target)
             }
+
+            self.derivedTestTargetsMap[item.product.id] = derivedTestTargets
         }
 
         self.buildToolPluginInvocationResults = buildToolPluginInvocationResults