Tests: Migrate 3 suites to Swift Testing

Migrate a few suites to Swift Teting, namely,
  - SwiftSDKCommandTests
  - MultiRootSupportTests
  - SwiftCommandStateTests

Depends on: #9012
Relates to: #8997
issue: rdar://157669245

Author: bkhouri

Sources/_InternalTestSupport/SwiftTesting+Tags.swift

@@ -41,8 +41,9 @@ extension Tag.Feature.Command {
     public enum Package {}
     public enum PackageRegistry {}
     @Tag public static var Build: Tag
-    @Tag public static var Test: Tag
     @Tag public static var Run: Tag
+    @Tag public static var Sdk: Tag
+    @Tag public static var Test: Tag
 }
 
 extension Tag.Feature.Command.Package {

Tests/CommandsTests/CommandsTestCase.swift

@@ -2,28 +2,37 @@
 //
 // This source file is part of the Swift open source project
 //
-// Copyright (c) 2014-2024 Apple Inc. and the Swift project authors
+// Copyright (c) 2014-2025 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
 // See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 //
 //===----------------------------------------------------------------------===//
+import Foundation
 
 import Basics
 import Commands
 import _InternalTestSupport
 import Workspace
-import XCTest
+import Testing
 
-final class MultiRootSupportTests: CommandsTestCase {
-    func testWorkspaceLoader() throws {
+@Suite(
+    .tags(
+        .TestSize.large,
+    ),
+)
+struct MultiRootSupportTests {
+    @Test
+    func workspaceLoader() throws {
         let fs = InMemoryFileSystem(emptyFiles: [
             "/tmp/test/dep/Package.swift",
             "/tmp/test/local/Package.swift",
         ])
         let path = AbsolutePath("/tmp/test/Workspace.xcworkspace")
-        try fs.writeFileContents(path.appending("contents.xcworkspacedata"), string:
+        try fs.writeFileContents(
+            path.appending("contents.xcworkspacedata"),
+            string:
                 """
                 <?xml version="1.0" encoding="UTF-8"?>
                 <Workspace
@@ -41,7 +50,9 @@ final class MultiRootSupportTests: CommandsTestCase {
         let observability = ObservabilitySystem.makeForTesting()
         let result = try XcodeWorkspaceLoader(fileSystem: fs, observabilityScope: observability.topScope).load(workspace: path)
 
-        XCTAssertNoDiagnostics(observability.diagnostics)
-        XCTAssertEqual(result.map{ $0.pathString }.sorted(), [AbsolutePath("/tmp/test/dep").pathString, AbsolutePath("/tmp/test/local").pathString])
+        expectNoDiagnostics(observability.diagnostics)
+        let actual = result.map { $0.pathString }.sorted()
+        let expected = [AbsolutePath("/tmp/test/dep").pathString, AbsolutePath("/tmp/test/local").pathString]
+        #expect(actual == expected)
     }
 }