Remove sourcekitd test hooks

Turns out that sourcekitd test hooks were a bad idea because of the following comment that I wrote:

```
`testHooks` are only considered when an instance is being created. If a sourcekitd instance at the given path already exists, its test hooks will be used.
```

During test execution in Xcode, we generate a bunch of `SourceKitServer` instances in the same process that all call `DynamicallyLoadedSourceKitD.getOrCreate`. Now, if `testDontReturnEmptyDiagnosticsIfDiagnosticRequestIsCancelled` is not the first test being executed in the process (which usually it is not), the test hooks in it won’t get used.

Switch back to using the preparation hooks, essentially reverting #1412 and keeping the following snippet to fix the underlying issue

```swift
// Poll until the `CancelRequestNotification` has been propagated to the request handling.
for _ in 0..<Int(defaultTimeout * 100) {
  if Task.isCancelled {
    break
  }
  usleep(10_000)
}
```

Author: ahoppen

Sources/Diagnose/RunSourcekitdRequestCommand.swift

@@ -55,8 +55,7 @@ public struct RunSourceKitdRequestCommand: AsyncParsableCommand {
         throw ExitCode(1)
       }
     let sourcekitd = try await DynamicallyLoadedSourceKitD.getOrCreate(
-      dylibPath: try! AbsolutePath(validating: sourcekitdPath),
-      testHooks: SourceKitDTestHooks()
+      dylibPath: try! AbsolutePath(validating: sourcekitdPath)
     )
 
     if let lineColumn = position?.split(separator: ":", maxSplits: 2).map(Int.init),

Sources/SourceKitD/DynamicallyLoadedSourceKitD.swift

@@ -26,27 +26,17 @@ extension sourcekitd_api_keys: @unchecked Sendable {}
 extension sourcekitd_api_requests: @unchecked Sendable {}
 extension sourcekitd_api_values: @unchecked Sendable {}
 
-public struct SourceKitDTestHooks: Sendable {
-  public var sourcekitdRequestDidStart: (@Sendable (SKDRequestDictionary) -> Void)?
-
-  public init(sourcekitdRequestDidStart: (@Sendable (SKDRequestDictionary) -> Void)? = nil) {
-    self.sourcekitdRequestDidStart = sourcekitdRequestDidStart
-  }
-}
-
 /// Wrapper for sourcekitd, taking care of initialization, shutdown, and notification handler
 /// multiplexing.
 ///
 /// Users of this class should not call the api functions `initialize`, `shutdown`, or
 /// `set_notification_handler`, which are global state managed internally by this class.
 public actor DynamicallyLoadedSourceKitD: SourceKitD {
   /// The path to the sourcekitd dylib.
-  private let path: AbsolutePath
+  public let path: AbsolutePath
 
   /// The handle to the dylib.
-  private let dylib: DLHandle
-
-  public let testHooks: SourceKitDTestHooks
+  let dylib: DLHandle
 
   /// The sourcekitd API functions.
   public let api: sourcekitd_api_functions_t
@@ -65,23 +55,18 @@ public actor DynamicallyLoadedSourceKitD: SourceKitD {
   /// List of notification handlers that will be called for each notification.
   private var notificationHandlers: [WeakSKDNotificationHandler] = []
 
-  /// If there is already a `sourcekitd` instance from the given return it, otherwise create a new one.
-  ///
-  /// `testHooks` are only considered when an instance is being created. If a sourcekitd instance at the given path
-  /// already exists, its test hooks will be used.
-  public static func getOrCreate(dylibPath: AbsolutePath, testHooks: SourceKitDTestHooks) async throws -> SourceKitD {
+  public static func getOrCreate(dylibPath: AbsolutePath) async throws -> SourceKitD {
     try await SourceKitDRegistry.shared
-      .getOrAdd(dylibPath, create: { try DynamicallyLoadedSourceKitD(dylib: dylibPath, testHooks: testHooks) })
+      .getOrAdd(dylibPath, create: { try DynamicallyLoadedSourceKitD(dylib: dylibPath) })
   }
 
-  init(dylib path: AbsolutePath, testHooks: SourceKitDTestHooks) throws {
+  init(dylib path: AbsolutePath) throws {
     self.path = path
     #if os(Windows)
     self.dylib = try dlopen(path.pathString, mode: [])
     #else
     self.dylib = try dlopen(path.pathString, mode: [.lazy, .local, .first])
     #endif
-    self.testHooks = testHooks
     self.api = try sourcekitd_api_functions_t(self.dylib)
     self.keys = sourcekitd_api_keys(api: self.api)
     self.requests = sourcekitd_api_requests(api: self.api)

Sources/SourceKitD/SourceKitD.swift

@@ -31,8 +31,6 @@ extension sourcekitd_api_request_handle_t: @unchecked Sendable {}
 /// *Implementors* are expected to handle initialization and shutdown, e.g. during `init` and
 /// `deinit` or by wrapping an existing sourcekitd session that outlives this object.
 public protocol SourceKitD: AnyObject, Sendable {
-  var testHooks: SourceKitDTestHooks { get }
-
   /// The sourcekitd API functions.
   var api: sourcekitd_api_functions_t { get }
 
@@ -101,8 +99,6 @@ extension SourceKitD {
   public func send(_ request: SKDRequestDictionary, fileContents: String?) async throws -> SKDResponseDictionary {
     log(request: request)
 
-    testHooks.sourcekitdRequestDidStart?(request)
-
     let sourcekitdResponse: SKDResponse = try await withCancellableCheckedThrowingContinuation { continuation in
       var handle: sourcekitd_api_request_handle_t? = nil
       api.send_request(request.dict, &handle) { response in

Sources/SourceKitLSP/SourceKitLSPServer+Options.swift

@@ -15,7 +15,6 @@ import LanguageServerProtocol
 import SKCore
 import SKSupport
 import SemanticIndex
-import SourceKitD
 
 import struct TSCBasic.AbsolutePath
 import struct TSCBasic.RelativePath
@@ -52,8 +51,6 @@ extension SourceKitLSPServer {
     /// Experimental features that are enabled.
     public var experimentalFeatures: Set<ExperimentalFeature>
 
-    public var sourcekitdTestHooks: SourceKitDTestHooks
-
     public var indexTestHooks: IndexTestHooks
 
     public init(
@@ -65,7 +62,6 @@ extension SourceKitLSPServer {
       generatedInterfacesPath: AbsolutePath = defaultDirectoryForGeneratedInterfaces,
       swiftPublishDiagnosticsDebounceDuration: TimeInterval = 2, /* 2s */
       experimentalFeatures: Set<ExperimentalFeature> = [],
-      sourcekitdTestHooks: SourceKitDTestHooks = SourceKitDTestHooks(),
       indexTestHooks: IndexTestHooks = IndexTestHooks()
     ) {
       self.buildSetup = buildSetup
@@ -76,7 +72,6 @@ extension SourceKitLSPServer {
       self.generatedInterfacesPath = generatedInterfacesPath
       self.swiftPublishDiagnosticsDebounceDuration = swiftPublishDiagnosticsDebounceDuration
       self.experimentalFeatures = experimentalFeatures
-      self.sourcekitdTestHooks = sourcekitdTestHooks
       self.indexTestHooks = indexTestHooks
     }
   }

Sources/SourceKitLSP/Swift/SwiftLanguageService.swift

@@ -195,10 +195,7 @@ public actor SwiftLanguageService: LanguageService, Sendable {
     guard let sourcekitd = toolchain.sourcekitd else { return nil }
     self.sourceKitLSPServer = sourceKitLSPServer
     self.swiftFormat = toolchain.swiftFormat
-    self.sourcekitd = try await DynamicallyLoadedSourceKitD.getOrCreate(
-      dylibPath: sourcekitd,
-      testHooks: options.sourcekitdTestHooks
-    )
+    self.sourcekitd = try await DynamicallyLoadedSourceKitD.getOrCreate(dylibPath: sourcekitd)
     self.capabilityRegistry = workspace.capabilityRegistry
     self.semanticIndexManager = workspace.semanticIndexManager
     self.serverOptions = options

Tests/DiagnoseTests/DiagnoseTests.swift

@@ -318,8 +318,7 @@ private class InProcessSourceKitRequestExecutor: SourceKitRequestExecutor {
     logger.info("Sending request: \(requestString)")
 
     let sourcekitd = try await DynamicallyLoadedSourceKitD.getOrCreate(
-      dylibPath: try! AbsolutePath(validating: sourcekitd.path),
-      testHooks: SourceKitDTestHooks()
+      dylibPath: try! AbsolutePath(validating: sourcekitd.path)
     )
     let response = try await sourcekitd.run(requestYaml: requestString)
 

Tests/SourceKitDTests/SourceKitDRegistryTests.swift

@@ -63,7 +63,6 @@ private nonisolated(unsafe) var nextToken = AtomicUInt32(initialValue: 0)
 
 final class FakeSourceKitD: SourceKitD {
   let token: UInt32
-  var testHooks: SourceKitDTestHooks { SourceKitDTestHooks() }
   var api: sourcekitd_api_functions_t { fatalError() }
   var keys: sourcekitd_api_keys { fatalError() }
   var requests: sourcekitd_api_requests { fatalError() }

Tests/SourceKitDTests/SourceKitDTests.swift

@@ -28,10 +28,7 @@ import class TSCBasic.Process
 final class SourceKitDTests: XCTestCase {
   func testMultipleNotificationHandlers() async throws {
     let sourcekitdPath = await ToolchainRegistry.forTesting.default!.sourcekitd!
-    let sourcekitd = try await DynamicallyLoadedSourceKitD.getOrCreate(
-      dylibPath: sourcekitdPath,
-      testHooks: SourceKitDTestHooks()
-    )
+    let sourcekitd = try await DynamicallyLoadedSourceKitD.getOrCreate(dylibPath: sourcekitdPath)
     let keys = sourcekitd.keys
     let path = DocumentURI(for: .swift).pseudoPath
 

Tests/SourceKitLSPTests/PullDiagnosticsTests.swift

@@ -310,15 +310,10 @@ final class PullDiagnosticsTests: XCTestCase {
   }
 
   func testDontReturnEmptyDiagnosticsIfDiagnosticRequestIsCancelled() async throws {
-    let diagnosticSourcekitdRequestDidStart = self.expectation(description: "diagnostic sourcekitd request did start")
     let diagnosticRequestCancelled = self.expectation(description: "diagnostic request cancelled")
     var serverOptions = SourceKitLSPServer.Options.testDefault
-    serverOptions.sourcekitdTestHooks.sourcekitdRequestDidStart = { request in
-      guard request.description.contains("source.request.diagnostics") else {
-        return
-      }
-      diagnosticSourcekitdRequestDidStart.fulfill()
-      self.wait(for: [diagnosticRequestCancelled], timeout: defaultTimeout)
+    serverOptions.indexTestHooks.preparationTaskDidStart = { _ in
+      await self.fulfillment(of: [diagnosticRequestCancelled], timeout: defaultTimeout)
       // Poll until the `CancelRequestNotification` has been propagated to the request handling.
       for _ in 0..<Int(defaultTimeout * 100) {
         if Task.isCancelled {
@@ -331,7 +326,9 @@ final class PullDiagnosticsTests: XCTestCase {
       files: [
         "Lib.swift": "let x: String = 1"
       ],
-      serverOptions: serverOptions
+      serverOptions: serverOptions,
+      enableBackgroundIndexing: true,
+      pollIndex: false
     )
     let (uri, _) = try project.openDocument("Lib.swift")
 
@@ -342,7 +339,6 @@ final class PullDiagnosticsTests: XCTestCase {
       XCTAssertEqual(result, .failure(ResponseError.cancelled))
       diagnosticResponseReceived.fulfill()
     }
-    try await fulfillmentOfOrThrow([diagnosticSourcekitdRequestDidStart])
     project.testClient.send(CancelRequestNotification(id: requestID))
     diagnosticRequestCancelled.fulfill()
     try await fulfillmentOfOrThrow([diagnosticResponseReceived])