[6.0] Build one test product for both Swift Testing and XCTest (with Swift Testing enabled by default.) (#7794)

**Explanation:** 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.
**Scope:** Implementation of Swift Testing/SwiftPM integration; touches
mostly `swift test` but affects `swift build` and `swift package init`
as well.
**Issue:** rdar://120864035
**Original PR:**
#7777,
#7789,
#7796
**Risk:** Moderate—refactors how we build and run tests.
**Testing:** Existing test coverage in the package as well as test
coverage in the Swift Testing package; additional integration testing
will be added once Swift Testing is in the toolchain.
**Reviewer:** @bnbarham @xedin @briancroom @dennisweissmann

---------

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

@@ -443,31 +443,29 @@ 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.productMap = productMap.mapValues(\.buildDescription)