Add a new test project type that uses a custom build server

Sources/BuildSystemIntegration/BuildSystemManager.swift

@@ -179,9 +179,9 @@ private extension BuildSystemSpec {
     _ createBuildSystem: @Sendable (_ connectionToSourceKitLSP: any Connection) async throws -> BuiltInBuildSystem?
   ) async -> BuildSystemAdapter? {
     let connectionToSourceKitLSP = LocalConnection(
-      receiverName: "BuildSystemManager for \(projectRoot.lastPathComponent)"
+      receiverName: "BuildSystemManager for \(projectRoot.lastPathComponent)",
+      handler: messagesToSourceKitLSPHandler
     )
-    connectionToSourceKitLSP.start(handler: messagesToSourceKitLSPHandler)
 
     let buildSystem = await orLog("Creating build system") {
       try await createBuildSystem(connectionToSourceKitLSP)
@@ -197,9 +197,9 @@ private extension BuildSystemSpec {
       buildSystemHooks: buildSystemHooks
     )
     let connectionToBuildSystem = LocalConnection(
-      receiverName: "\(type(of: buildSystem)) for \(projectRoot.lastPathComponent)"
+      receiverName: "\(type(of: buildSystem)) for \(projectRoot.lastPathComponent)",
+      handler: buildSystemAdapter
     )
-    connectionToBuildSystem.start(handler: buildSystemAdapter)
     return .builtIn(buildSystemAdapter, connectionToBuildSystem: connectionToBuildSystem)
   }
 
@@ -266,9 +266,9 @@ private extension BuildSystemSpec {
       #endif
     case .injected(let injector):
       let connectionToSourceKitLSP = LocalConnection(
-        receiverName: "BuildSystemManager for \(projectRoot.lastPathComponent)"
+        receiverName: "BuildSystemManager for \(projectRoot.lastPathComponent)",
+        handler: messagesToSourceKitLSPHandler
       )
-      connectionToSourceKitLSP.start(handler: messagesToSourceKitLSPHandler)
       return .injected(
         await injector(projectRoot, connectionToSourceKitLSP)
       )
@@ -510,8 +510,7 @@ package actor BuildSystemManager: QueueBasedMessageHandler {
           connectionToSourceKitLSP: legacyBuildServer.connectionToSourceKitLSP,
           buildSystemHooks: buildSystemHooks
         )
-        let connectionToBuildSystem = LocalConnection(receiverName: "Legacy BSP server")
-        connectionToBuildSystem.start(handler: adapter)
+        let connectionToBuildSystem = LocalConnection(receiverName: "Legacy BSP server", handler: adapter)
         self.buildSystemAdapter = .builtIn(adapter, connectionToBuildSystem: connectionToBuildSystem)
       }
       Task {

Sources/BuildSystemIntegration/CMakeLists.txt

@@ -19,8 +19,7 @@ add_library(BuildSystemIntegration STATIC
   LegacyBuildServerBuildSystem.swift
   MainFilesProvider.swift
   SplitShellCommand.swift
-  SwiftPMBuildSystem.swift
-  TestBuildSystem.swift)
+  SwiftPMBuildSystem.swift)
 set_target_properties(BuildSystemIntegration PROPERTIES
   INTERFACE_INCLUDE_DIRECTORIES ${CMAKE_Swift_MODULE_DIRECTORY})
 target_link_libraries(BuildSystemIntegration PUBLIC

Sources/BuildSystemIntegration/LegacyBuildServerBuildSystem.swift

@@ -73,8 +73,10 @@ actor LegacyBuildServerBuildSystem: MessageHandler, BuiltInBuildSystem {
     self.configPath = configPath
     self.indexDatabasePath = nil
     self.indexStorePath = nil
-    self.connectionToSourceKitLSP = LocalConnection(receiverName: "BuildSystemManager")
-    await self.connectionToSourceKitLSP.start(handler: externalBuildSystemAdapter.messagesToSourceKitLSPHandler)
+    self.connectionToSourceKitLSP = LocalConnection(
+      receiverName: "BuildSystemManager",
+      handler: await externalBuildSystemAdapter.messagesToSourceKitLSPHandler
+    )
     await externalBuildSystemAdapter.changeMessageToSourceKitLSPHandler(to: self)
     self.buildServer = await externalBuildSystemAdapter.connectionToBuildServer
   }

Sources/LanguageServerProtocolExtensions/LocalConnection.swift

@@ -56,6 +56,11 @@ package final class LocalConnection: Connection, Sendable {
     self.name = receiverName
   }
 
+  package convenience init(receiverName: String, handler: MessageHandler) {
+    self.init(receiverName: receiverName)
+    self.start(handler: handler)
+  }
+
   deinit {
     queue.sync {
       if state != .closed {

Sources/BuildSystemIntegration/TestBuildSystem.swift → Sources/SKTestSupport/CustomBuildServerTestProject.swift

@@ -2,53 +2,61 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2020 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 https://swift.org/LICENSE.txt for license information
 // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 //
 //===----------------------------------------------------------------------===//
 
-import Foundation
+import BuildSystemIntegration
 import LanguageServerProtocolExtensions
 import SKLogging
-import SKOptions
+import SourceKitLSP
+import SwiftExtensions
 import ToolchainRegistry
+import XCTest
 
 #if compiler(>=6)
 package import BuildServerProtocol
+package import Foundation
 package import LanguageServerProtocol
+package import SKOptions
 #else
 import BuildServerProtocol
+import Foundation
 import LanguageServerProtocol
+import SKOptions
 #endif
 
-/// Build system to be used for testing BuildSystem and BuildSystemDelegate functionality with SourceKitLSPServer
-/// and other components.
-package actor TestBuildSystem: MessageHandler {
-  private let connectionToSourceKitLSP: any Connection
-
-  /// Build settings by file.
-  private var buildSettingsByFile: [DocumentURI: TextDocumentSourceKitOptionsResponse] = [:]
-
-  package func setBuildSettings(for uri: DocumentURI, to buildSettings: TextDocumentSourceKitOptionsResponse?) {
-    buildSettingsByFile[uri] = buildSettings
-    connectionToSourceKitLSP.send(OnBuildTargetDidChangeNotification(changes: nil))
-  }
+// MARK: - CustomBuildServer
 
-  private let initializeData: SourceKitInitializeBuildResponseData
+/// A build server that can be injected into `CustomBuildServerTestProject`.
+package protocol CustomBuildServer: MessageHandler {
+  init(projectRoot: URL, connectionToSourceKitLSP: any Connection)
 
-  package init(
-    initializeData: SourceKitInitializeBuildResponseData = SourceKitInitializeBuildResponseData(
-      sourceKitOptionsProvider: true
-    ),
-    connectionToSourceKitLSP: any Connection
-  ) {
-    self.initializeData = initializeData
-    self.connectionToSourceKitLSP = connectionToSourceKitLSP
-  }
+  func initializeBuildRequest(_ request: InitializeBuildRequest) async throws -> InitializeBuildResponse
+  func onBuildInitialized(_ notification: OnBuildInitializedNotification) throws
+  func buildShutdown(_ request: BuildShutdownRequest) async throws -> VoidResponse
+  func onBuildExit(_ notification: OnBuildExitNotification) throws
+  func workspaceBuildTargetsRequest(
+    _ request: WorkspaceBuildTargetsRequest
+  ) async throws -> WorkspaceBuildTargetsResponse
+  func buildTargetSourcesRequest(_ request: BuildTargetSourcesRequest) async throws -> BuildTargetSourcesResponse
+  func textDocumentSourceKitOptionsRequest(
+    _ request: TextDocumentSourceKitOptionsRequest
+  ) async throws -> TextDocumentSourceKitOptionsResponse?
+  func prepareTarget(_ request: BuildTargetPrepareRequest) async throws -> VoidResponse
+  func waitForBuildSystemUpdates(request: WorkspaceWaitForBuildSystemUpdatesRequest) async -> VoidResponse
+  nonisolated func onWatchedFilesDidChange(_ notification: OnWatchedFilesDidChangeNotification) throws
+  func workspaceWaitForBuildSystemUpdatesRequest(
+    _ request: WorkspaceWaitForBuildSystemUpdatesRequest
+  ) async throws -> VoidResponse
+  nonisolated func cancelRequest(_ notification: CancelRequestNotification) throws
+}
 
+extension CustomBuildServer {
   package nonisolated func handle(_ notification: some NotificationType) {
     do {
       switch notification {
@@ -64,7 +72,7 @@ package actor TestBuildSystem: MessageHandler {
         throw ResponseError.methodNotFound(type(of: notification).method)
       }
     } catch {
-      logger.error("Error while handling BSP notification")
+      logger.error("Error while handling BSP notification: \(error.forLogging)")
     }
   }
 
@@ -102,10 +110,18 @@ package actor TestBuildSystem: MessageHandler {
       reply(.failure(ResponseError.methodNotFound(type(of: request).method)))
     }
   }
+}
 
-  func initializeBuildRequest(_ request: InitializeBuildRequest) async throws -> InitializeBuildResponse {
-    return InitializeBuildResponse(
-      displayName: "TestBuildSystem",
+package extension CustomBuildServer {
+  // MARK: Helper functions for the implementation of BSP methods
+
+  func initializationResponse(
+    initializeData: SourceKitInitializeBuildResponseData = SourceKitInitializeBuildResponseData(
+      sourceKitOptionsProvider: true
+    )
+  ) -> InitializeBuildResponse {
+    InitializeBuildResponse(
+      displayName: "\(type(of: self))",
       version: "",
       bspVersion: "2.2.0",
       capabilities: BuildServerCapabilities(),
@@ -114,17 +130,25 @@ package actor TestBuildSystem: MessageHandler {
     )
   }
 
-  nonisolated func onBuildInitialized(_ notification: OnBuildInitializedNotification) throws {
-    // Nothing to do
+  func dummyTargetSourcesResponse(_ files: some Sequence<DocumentURI>) -> BuildTargetSourcesResponse {
+    return BuildTargetSourcesResponse(items: [
+      SourcesItem(target: .dummy, sources: files.map { SourceItem(uri: $0, kind: .file, generated: false) })
+    ])
   }
 
+  // MARK: Default implementation for all build server methods that usually don't need customization.
+
+  func initializeBuildRequest(_ request: InitializeBuildRequest) async throws -> InitializeBuildResponse {
+    return initializationResponse()
+  }
+
+  nonisolated func onBuildInitialized(_ notification: OnBuildInitializedNotification) throws {}
+
   func buildShutdown(_ request: BuildShutdownRequest) async throws -> VoidResponse {
     return VoidResponse()
   }
 
-  nonisolated func onBuildExit(_ notification: OnBuildExitNotification) throws {
-    // Nothing to do
-  }
+  nonisolated func onBuildExit(_ notification: OnBuildExitNotification) throws {}
 
   func workspaceBuildTargetsRequest(
     _ request: WorkspaceBuildTargetsRequest
@@ -142,32 +166,15 @@ package actor TestBuildSystem: MessageHandler {
     ])
   }
 
-  func buildTargetSourcesRequest(_ request: BuildTargetSourcesRequest) async throws -> BuildTargetSourcesResponse {
-    return BuildTargetSourcesResponse(items: [
-      SourcesItem(
-        target: .dummy,
-        sources: buildSettingsByFile.keys.map { SourceItem(uri: $0, kind: .file, generated: false) }
-      )
-    ])
-  }
-
-  func textDocumentSourceKitOptionsRequest(
-    _ request: TextDocumentSourceKitOptionsRequest
-  ) async throws -> TextDocumentSourceKitOptionsResponse? {
-    return buildSettingsByFile[request.textDocument.uri]
-  }
-
   func prepareTarget(_ request: BuildTargetPrepareRequest) async throws -> VoidResponse {
     return VoidResponse()
   }
 
-  package func waitForBuildSystemUpdates(request: WorkspaceWaitForBuildSystemUpdatesRequest) async -> VoidResponse {
+  func waitForBuildSystemUpdates(request: WorkspaceWaitForBuildSystemUpdatesRequest) async -> VoidResponse {
     return VoidResponse()
   }
 
-  nonisolated func onWatchedFilesDidChange(_ notification: OnWatchedFilesDidChangeNotification) throws {
-    // Not watching any files
-  }
+  nonisolated func onWatchedFilesDidChange(_ notification: OnWatchedFilesDidChangeNotification) throws {}
 
   func workspaceWaitForBuildSystemUpdatesRequest(
     _ request: WorkspaceWaitForBuildSystemUpdatesRequest
@@ -177,3 +184,40 @@ package actor TestBuildSystem: MessageHandler {
 
   nonisolated func cancelRequest(_ notification: CancelRequestNotification) throws {}
 }
+
+// MARK: - CustomBuildServerTestProject
+
+/// A test project that launches a custom build server in-process.
+///
+/// In contrast to `ExternalBuildServerTestProject`, the custom build system runs in-process and is implemented in
+/// Swift.
+package final class CustomBuildServerTestProject<BuildServer: CustomBuildServer>: MultiFileTestProject {
+  private let buildServerBox = ThreadSafeBox<BuildServer?>(initialValue: nil)
+
+  package init(
+    files: [RelativeFileLocation: String],
+    buildServer buildServerType: BuildServer.Type,
+    options: SourceKitLSPOptions? = nil,
+    enableBackgroundIndexing: Bool = false,
+    testName: String = #function
+  ) async throws {
+    let hooks: Hooks = Hooks(
+      buildSystemHooks: BuildSystemHooks(injectBuildServer: { [buildServerBox] projectRoot, connectionToSourceKitLSP in
+        let buildServer = BuildServer(projectRoot: projectRoot, connectionToSourceKitLSP: connectionToSourceKitLSP)
+        buildServerBox.value = buildServer
+        return LocalConnection(receiverName: "TestBuildSystem", handler: buildServer)
+      })
+    )
+    try await super.init(
+      files: files,
+      options: options,
+      hooks: hooks,
+      enableBackgroundIndexing: enableBackgroundIndexing,
+      testName: testName
+    )
+  }
+
+  package func buildServer(file: StaticString = #filePath, line: UInt = #line) throws -> BuildServer {
+    try XCTUnwrap(buildServerBox.value, "Accessing build server before it has been created", file: file, line: line)
+  }
+}

Sources/SKTestSupport/BuildServerTestProject.swift → Sources/SKTestSupport/ExternalBuildServerTestProject.swift

@@ -59,7 +59,7 @@ private let skTestSupportInputsDirectory: URL = {
 ///
 /// The build server can contain `$SDK_ARGS`, which will replaced by `"-sdk", "/path/to/sdk"` on macOS and by an empty
 /// string on all other platforms.
-package class BuildServerTestProject: MultiFileTestProject {
+package class ExternalBuildServerTestProject: MultiFileTestProject {
   package init(
     files: [RelativeFileLocation: String],
     buildServerConfigLocation: RelativeFileLocation = ".bsp/sourcekit-lsp.json",