Expose computeTestTargetsForExecutableTargets via SPI (#7455)

Bringing back `computeTestTargetsForExecutableTargets` on `ModulesGraph`
via `@_spi(SwiftPMInternal)`.

Author: MaxDesiatov

Sources/PackageGraph/ModulesGraph.swift

@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift open source project
 //
-// Copyright (c) 2014-2021 Apple Inc. and the Swift project authors
+// Copyright (c) 2014-2024 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See http://swift.org/LICENSE.txt for license information
@@ -23,13 +23,31 @@ enum PackageGraphError: Swift.Error {
     case cycleDetected((path: [Manifest], cycle: [Manifest]))
 
     /// The product dependency not found.
-    case productDependencyNotFound(package: String, targetName: String, dependencyProductName: String, dependencyPackageName: String?, dependencyProductInDecl: Bool, similarProductName: String?, packageContainingSimilarProduct: String?)
+    case productDependencyNotFound(
+        package: String,
+        targetName: String,
+        dependencyProductName: String,
+        dependencyPackageName: String?,
+        dependencyProductInDecl: Bool,
+        similarProductName: String?,
+        packageContainingSimilarProduct: String?
+    )
 
     /// The package dependency already satisfied by a different dependency package
-    case dependencyAlreadySatisfiedByIdentifier(package: String, dependencyLocation: String, otherDependencyURL: String, identity: PackageIdentity)
+    case dependencyAlreadySatisfiedByIdentifier(
+        package: String,
+        dependencyLocation: String,
+        otherDependencyURL: String,
+        identity: PackageIdentity
+    )
 
     /// The package dependency already satisfied by a different dependency package
-    case dependencyAlreadySatisfiedByName(package: String, dependencyLocation: String, otherDependencyURL: String, name: String)
+    case dependencyAlreadySatisfiedByName(
+        package: String,
+        dependencyLocation: String,
+        otherDependencyURL: String,
+        name: String
+    )
 
     /// The product dependency was found but the package name was not referenced correctly (tools version > 5.2).
     case productDependencyMissingPackage(
@@ -38,15 +56,23 @@ enum PackageGraphError: Swift.Error {
         packageIdentifier: String
     )
     /// Dependency between a plugin and a dependent target/product of a given type is unsupported
-    case unsupportedPluginDependency(targetName: String, dependencyName: String, dependencyType: String, dependencyPackage: String?)
+    case unsupportedPluginDependency(
+        targetName: String,
+        dependencyName: String,
+        dependencyType: String,
+        dependencyPackage: String?
+    )
+
     /// A product was found in multiple packages.
     case duplicateProduct(product: String, packages: [Package])
 
     /// Duplicate aliases for a target found in a product.
-    case multipleModuleAliases(target: String,
-                               product: String,
-                               package: String,
-                               aliases: [String])
+    case multipleModuleAliases(
+        target: String,
+        product: String,
+        package: String,
+        aliases: [String]
+    )
 }
 
 @available(*,
@@ -187,7 +213,8 @@ public struct ModulesGraph {
     }
 
     /// Computes a map from each executable target in any of the root packages to the corresponding test targets.
-    func computeTestTargetsForExecutableTargets() throws -> [ResolvedTarget.ID: [ResolvedTarget]] {
+    @_spi(SwiftPMInternal)
+    public func computeTestTargetsForExecutableTargets() throws -> [ResolvedTarget.ID: [ResolvedTarget]] {
         var result = [ResolvedTarget.ID: [ResolvedTarget]]()
 
         let rootTargets = IdentifiableSet(rootPackages.flatMap { $0.targets })

Tests/FunctionalTests/PluginTests.swift

@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift open source project
 //
-// Copyright (c) 2021-2022 Apple Inc. and the Swift project authors
+// Copyright (c) 2021-2024 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See http://swift.org/LICENSE.txt for license information
@@ -11,6 +11,8 @@
 //===----------------------------------------------------------------------===//
 
 import Basics
+
+@_spi(SwiftPMInternal)
 @testable import PackageGraph
 import PackageLoading
 import PackageModel
@@ -19,8 +21,7 @@ import SPMTestSupport
 import Workspace
 import XCTest
 
-class PluginTests: XCTestCase {
-    
+final class PluginTests: XCTestCase {
     func testUseOfBuildToolPluginTargetByExecutableInSamePackage() throws {
         // Only run the test if the environment in which we're running actually supports Swift concurrency (which the plugin APIs require).
         try XCTSkipIf(!UserToolchain.default.supportsSwiftConcurrency(), "skipping because test environment doesn't support concurrency")