Make SKSwiftPMWorkspaceTests build in Swift 6 mode

Author: ahoppen

Sources/SKTestSupport/TestSourceKitLSPClient.swift

@@ -22,7 +22,7 @@ import XCTest
 
 extension SourceKitLSPServer.Options {
   /// The default SourceKitLSPServer options for testing.
-  public static var testDefault = Self(swiftPublishDiagnosticsDebounceDuration: 0)
+  public static let testDefault = Self(swiftPublishDiagnosticsDebounceDuration: 0)
 }
 
 /// A mock SourceKit-LSP client (aka. a mock editor) that behaves like an editor

Sources/SKTestSupport/Utils.swift

@@ -70,7 +70,7 @@ public func testScratchDir(testName: String = #function) throws -> URL {
 /// The temporary directory will be deleted at the end of `directory` unless the
 /// `SOURCEKITLSP_KEEP_TEST_SCRATCH_DIR` environment variable is set.
 public func withTestScratchDir<T>(
-  _ body: @Sendable (AbsolutePath) async throws -> T,
+  @_inheritActorContext _ body: @Sendable (AbsolutePath) async throws -> T,
   testName: String = #function
 ) async throws -> T {
   let scratchDirectory = try testScratchDir(testName: testName)

Tests/SKSwiftPMWorkspaceTests/SwiftPMBuildSystemTests.swift

@@ -24,7 +24,7 @@ import XCTest
 import struct PackageModel.BuildFlags
 
 #if canImport(SPMBuildCore)
-import SPMBuildCore
+@preconcurrency import SPMBuildCore
 #endif
 
 fileprivate extension SwiftPMBuildSystem {