Teach swift package add-target --type test about swift-testing

Introduce a command-line argument `--testing-library` to the add-target
command to specify which test library to generate the test for. This
can be 'xctest' (the prior XCTest behavior), 'swift-testing' (to use the
new swift-testing library), or 'none' (for no test library at all).

For the new swift-testing generation, also add the appropriate package
and test target dependency, along with a stub testsuite to start from.

Fixes #7478

Author: DougGregor

Sources/Commands/PackageCommands/AddTarget.swift

@@ -21,6 +21,8 @@ import TSCBasic
 import TSCUtility
 import Workspace
 
+extension AddTarget.TestHarness: ExpressibleByArgument { }
+
 extension SwiftPackageCommand {
     struct AddTarget: SwiftCommand {
         /// The type of target that can be specified on the command line.
@@ -58,6 +60,9 @@ extension SwiftPackageCommand {
         @Option(help: "The checksum for a remote binary target")
         var checksum: String?
 
+        @Option(help: "The testing library to use when generating test targets, which can be one of 'xctest', 'swift-testing', or 'none'")
+        var testingLibrary: PackageModelSyntax.AddTarget.TestHarness = .default
+
         func run(_ swiftCommandState: SwiftCommandState) throws {
             let workspace = try swiftCommandState.getActiveWorkspace()
 
@@ -110,6 +115,7 @@ extension SwiftPackageCommand {
             let editResult = try PackageModelSyntax.AddTarget.addTarget(
                 target,
                 to: manifestSyntax,
+                configuration: .init(testHarness: testingLibrary),
                 installedSwiftPMConfiguration: swiftCommandState
                   .getHostToolchain()
                   .installedSwiftPMConfiguration

Sources/PackageModel/InstalledSwiftPMConfiguration.swift

@@ -31,6 +31,7 @@ public struct InstalledSwiftPMConfiguration: Codable {
 
     let version: Int
     public let swiftSyntaxVersionForMacroTemplate: Version
+    public let swiftTestingVersionForTestTemplate: Version
 
     public static var `default`: InstalledSwiftPMConfiguration {
         return .init(
@@ -40,6 +41,12 @@ public struct InstalledSwiftPMConfiguration: Codable {
                 minor: 0,
                 patch: 0,
                 prereleaseIdentifier: "latest"
+            ),
+            swiftTestingVersionForTestTemplate: .init(
+                major: 0,
+                minor: 7,
+                patch: 0,
+                prereleaseIdentifier: nil
             )
         )
     }

Sources/PackageModelSyntax/AddTarget.swift

@@ -30,12 +30,40 @@ public struct AddTarget {
         "cxxLanguageStandard"
     ]
 
+    /// The kind of test harness to use. This isn't part of the manifest
+    /// itself, but is used to guide the generation process.
+    public enum TestHarness: String, Codable {
+        /// Don't use any library
+        case none
+
+        /// Create a test using the XCTest library.
+        case xctest
+
+        /// Create a test using the swift-testing package.
+        case swiftTesting = "swift-testing"
+
+        /// The default testing library to use.
+        public static var `default`: TestHarness = .xctest
+    }
+
+    /// Additional configuration information to guide the package editing
+    /// process.
+    public struct Configuration {
+        /// The test harness to use.
+        public var testHarness: TestHarness
+
+        public init(testHarness: TestHarness = .default) {
+            self.testHarness = testHarness
+        }
+    }
+
     /// Add the given target to the manifest, producing a set of edit results
     /// that updates the manifest and adds some source files to stub out the
     /// new target.
     public static func addTarget(
         _ target: TargetDescription,
         to manifest: SourceFileSyntax,
+        configuration: Configuration = .init(),
         installedSwiftPMConfiguration: InstalledSwiftPMConfiguration = .default
     ) throws -> PackageEditResult {
         // Make sure we have a suitable tools version in the manifest.
@@ -49,10 +77,20 @@ public struct AddTarget {
         // content when needed.
         var target = target
 
-        // Macro targets need to depend on a couple of libraries from
-        // SwiftSyntax.
-        if target.type == .macro {
+        // Add dependencies needed for various targets.
+        switch target.type {
+        case .macro:
+            // Macro targets need to depend on a couple of libraries from
+            // 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;
         }
 
         var newPackageCall = try packageCall.appendingToArrayArgument(
@@ -84,6 +122,7 @@ public struct AddTarget {
         addPrimarySourceFile(
             outerPath: outerPath,
             target: target,
+            configuration: configuration,
             to: &auxiliaryFiles
         )
 
@@ -124,6 +163,17 @@ 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;
         }
 
@@ -140,6 +190,7 @@ public struct AddTarget {
     fileprivate static func addPrimarySourceFile(
         outerPath: RelativePath,
         target: TargetDescription,
+        configuration: Configuration,
         to auxiliaryFiles: inout AuxiliaryFiles
     ) {
         let sourceFilePath = outerPath.appending(
@@ -153,7 +204,17 @@ public struct AddTarget {
 
         // Add appropriate test module dependencies.
         if target.type == .test {
-            importModuleNames.append("XCTest")
+            switch configuration.testHarness {
+            case .none: 
+                break
+
+            case .xctest:
+                importModuleNames.append("XCTest")
+
+            case .swiftTesting: 
+                // Import is handled by the added dependency.
+                break
+            }
         }
 
         let importDecls = importModuleNames.lazy.sorted().map { name in
@@ -184,14 +245,35 @@ public struct AddTarget {
             """
 
         case .test:
-            """
-            \(imports)
-            class \(raw: target.name): XCTestCase {
-                func test\(raw: target.name)() {
-                    XCTAssertEqual(42, 17 + 25)
+            switch configuration.testHarness {
+            case .none:
+                """
+                \(imports)
+                // Test code here
+                """
+
+            case .xctest:
+                """
+                \(imports)
+                class \(raw: target.name): XCTestCase {
+                    func test\(raw: target.name)() {
+                        XCTAssertEqual(42, 17 + 25)
+                    }
+                }
+                """
+
+            case .swiftTesting:
+                """
+                \(imports)
+                @Suite
+                struct \(raw: target.name)Tests {
+                    @Test("\(raw: target.name) tests")
+                    func tests() {
+                        #expect(42 == 17 + 25)
+                    }
                 }
+                """
             }
-            """
 
         case .regular:
             """
@@ -298,3 +380,35 @@ 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
+        )
+    }
+}

Tests/PackageModelSyntaxTests/ManifestEditTests.swift

@@ -564,6 +564,53 @@ class ManifestEditTests: XCTestCase {
         }
     }
 
+    func testAddSwiftTestingTestTarget() throws {
+        try assertManifestRefactor("""
+            // swift-tools-version: 5.5
+            let package = Package(
+                name: "packages"
+            )
+            """,
+            expectedManifest: """
+            // swift-tools-version: 5.5
+            let package = Package(
+                name: "packages",
+                dependencies: [
+                    .package(url: "https://github.com/apple/swift-testing.git", from: "0.7.0"),
+                ],
+                targets: [
+                    .testTarget(
+                        name: "MyTest",
+                        dependencies: [ .product(name: "Testing", package: "swift-testing") ]
+                    ),
+                ]
+            )
+            """,
+            expectedAuxiliarySources: [
+                RelativePath("Tests/MyTest/MyTest.swift") : """
+                import Testing
+
+                @Suite
+                struct MyTestTests {
+                    @Test("MyTest tests")
+                    func tests() {
+                        #expect(42 == 17 + 25)
+                    }
+                }
+                """
+            ]) { manifest in
+            try AddTarget.addTarget(
+                TargetDescription(
+                    name: "MyTest",
+                    type: .test
+                ),
+                to: manifest,
+                configuration: .init(
+                    testHarness: .swiftTesting
+                )
+            )
+        }
+    }
 }
 
 

Utilities/config.json

@@ -1 +1,3 @@
-{"version":1,"swiftSyntaxVersionForMacroTemplate":{"major":600,"minor":0,"patch":0, "prereleaseIdentifier":"latest"}}
+{"version":1,
+  "swiftSyntaxVersionForMacroTemplate":{"major":600,"minor":0,"patch":0, "prereleaseIdentifier":"latest"},
+  "swiftTestingVersionForTestTemplate":{"major":0,"minor":7,"patch":0}}