Implement a syntactic workspace-wide test index

This workspace-wide syntactic test index is used for two purposes:
- It is used for XCTests instead of the semantic index for files that have on-disk or in-memory modifications to files
- It is uses for swift-testing tests, which are only discovered syntactically.

rdar://119191037

Author: ahoppen

Sources/SKCore/BuildServerBuildSystem.swift

@@ -316,6 +316,17 @@ extension BuildServerBuildSystem: BuildSystem {
 
     return .unhandled
   }
+
+  public func testFiles() async -> [DocumentURI] {
+    // BuildServerBuildSystem does not support syntactic test discovery
+    // (https://github.com/apple/sourcekit-lsp/issues/1173).
+    return []
+  }
+
+  public func addTestFilesDidChangeCallback(_ callback: @escaping () async -> Void) {
+    // BuildServerBuildSystem does not support syntactic test discovery
+    // (https://github.com/apple/sourcekit-lsp/issues/1173).
+  }
 }
 
 private func loadBuildServerConfig(path: AbsolutePath, fileSystem: FileSystem) throws -> BuildServerConfig {

Sources/SKCore/BuildSystem.swift

@@ -87,6 +87,18 @@ public protocol BuildSystem: AnyObject, Sendable {
   func filesDidChange(_ events: [FileEvent]) async
 
   func fileHandlingCapability(for uri: DocumentURI) async -> FileHandlingCapability
+
+  /// Returns the list of files that might contain test cases.
+  ///
+  /// The returned file list is an over-approximation. It might contain tests from non-test targets or files that don't
+  /// actually contain any tests. Keeping this list as minimal as possible helps reduce the amount of work that the
+  /// syntactic test indexer needs to perform.
+  func testFiles() async -> [DocumentURI]
+
+  /// Adds a callback that should be called when the value returned by `testFiles()` changes.
+  ///
+  /// The callback might also be called without an actual change to `testFiles`.
+  func addTestFilesDidChangeCallback(_ callback: @Sendable @escaping () async -> Void) async
 }
 
 public let buildTargetsNotSupported =

Sources/SKCore/BuildSystemManager.swift

@@ -176,6 +176,10 @@ extension BuildSystemManager {
       fallbackBuildSystem != nil ? .fallback : .unhandled
     )
   }
+
+  public func testFiles() async -> [DocumentURI] {
+    return await buildSystem?.testFiles() ?? []
+  }
 }
 
 extension BuildSystemManager: BuildSystemDelegate {

Sources/SKCore/CompilationDatabaseBuildSystem.swift

@@ -39,6 +39,9 @@ public actor CompilationDatabaseBuildSystem {
   /// Delegate to handle any build system events.
   public weak var delegate: BuildSystemDelegate? = nil
 
+  /// Callbacks that should be called if the list of possible test files has changed.
+  public var testFilesDidChangeCallbacks: [() async -> Void] = []
+
   public func setDelegate(_ delegate: BuildSystemDelegate?) async {
     self.delegate = delegate
   }
@@ -167,6 +170,9 @@ extension CompilationDatabaseBuildSystem: BuildSystem {
     if let delegate = self.delegate {
       await delegate.fileBuildSettingsChanged(self.watchedFiles)
     }
+    for testFilesDidChangeCallback in testFilesDidChangeCallbacks {
+      await testFilesDidChangeCallback()
+    }
   }
 
   public func filesDidChange(_ events: [FileEvent]) async {
@@ -185,4 +191,12 @@ extension CompilationDatabaseBuildSystem: BuildSystem {
       return .unhandled
     }
   }
+
+  public func testFiles() async -> [DocumentURI] {
+    return compdb?.allCommands.map { DocumentURI($0.url) } ?? []
+  }
+
+  public func addTestFilesDidChangeCallback(_ callback: @escaping () async -> Void) async {
+    testFilesDidChangeCallbacks.append(callback)
+  }
 }

Sources/SKSupport/AsyncQueue.swift

@@ -16,6 +16,8 @@ import Foundation
 /// array.
 private protocol AnyTask: Sendable {
   func waitForCompletion() async
+
+  func cancel()
 }
 
 extension Task: AnyTask {
@@ -89,6 +91,16 @@ public final class AsyncQueue<TaskMetadata: DependencyTracker>: Sendable {
 
   public init() {}
 
+  public func cancelTasks(where filter: (TaskMetadata) -> Bool) {
+    pendingTasks.withLock { pendingTasks in
+      for task in pendingTasks {
+        if filter(task.metadata) {
+          task.task.cancel()
+        }
+      }
+    }
+  }
+
   /// Schedule a new closure to be executed on the queue.
   ///
   /// If this is a serial queue, all previously added tasks are guaranteed to

Sources/SKSwiftPMWorkspace/SwiftPMBuildSystem.swift

@@ -81,6 +81,9 @@ public actor SwiftPMBuildSystem {
     self.delegate = delegate
   }
 
+  /// Callbacks that should be called if the list of possible test files has changed.
+  public var testFilesDidChangeCallbacks: [() async -> Void] = []
+
   let workspacePath: TSCAbsolutePath
   /// The directory containing `Package.swift`.
   public var projectRoot: TSCAbsolutePath
@@ -267,6 +270,9 @@ extension SwiftPMBuildSystem {
     }
     await delegate.fileBuildSettingsChanged(self.watchedFiles)
     await delegate.fileHandlingCapabilityChanged()
+    for testFilesDidChangeCallback in testFilesDidChangeCallbacks {
+      await testFilesDidChangeCallback()
+    }
   }
 }
 
@@ -380,6 +386,15 @@ extension SwiftPMBuildSystem: SKCore.BuildSystem {
       return .unhandled
     }
   }
+
+  public func testFiles() -> [DocumentURI] {
+    // We should only include source files from test targets (https://github.com/apple/sourcekit-lsp/issues/1174).
+    return fileToTarget.map { DocumentURI($0.key.asURL) }
+  }
+
+  public func addTestFilesDidChangeCallback(_ callback: @Sendable @escaping () async -> Void) async {
+    testFilesDidChangeCallbacks.append(callback)
+  }
 }
 
 extension SwiftPMBuildSystem {

Sources/SKTestSupport/IndexedSingleSwiftFileTestProject.swift

@@ -68,6 +68,25 @@ public struct IndexedSingleSwiftFileTestProject {
 
     if let sdk = TibsBuilder.defaultSDKPath {
       compilerArguments += ["-sdk", sdk]
+
+      // The following are needed so we can import XCTest
+      let sdkUrl = URL(fileURLWithPath: sdk)
+      let usrLibDir =
+        sdkUrl
+        .deletingLastPathComponent()
+        .deletingLastPathComponent()
+        .appendingPathComponent("usr")
+        .appendingPathComponent("lib")
+      let frameworksDir =
+        sdkUrl
+        .deletingLastPathComponent()
+        .deletingLastPathComponent()
+        .appendingPathComponent("Library")
+        .appendingPathComponent("Frameworks")
+      compilerArguments += [
+        "-I", usrLibDir.path,
+        "-F", frameworksDir.path,
+      ]
     }
 
     let compilationDatabase = JSONCompilationDatabase(

Sources/SKTestSupport/MultiFileTestProject.swift

@@ -142,4 +142,13 @@ public class MultiFileTestProject {
     }
     return DocumentPositions(markedText: fileData.markedText)[marker]
   }
+
+  public func range(from fromMarker: String, to toMarker: String, in fileName: String) throws -> Range<Position> {
+    return try position(of: fromMarker, in: fileName)..<position(of: toMarker, in: fileName)
+  }
+
+  public func location(from fromMarker: String, to toMarker: String, in fileName: String) throws -> Location {
+    let range = try self.range(from: fromMarker, to: toMarker, in: fileName)
+    return Location(uri: try self.uri(for: fileName), range: range)
+  }
 }

Sources/SKTestSupport/SwiftPMTestProject.swift

@@ -40,6 +40,7 @@ public class SwiftPMTestProject: MultiFileTestProject {
     manifest: String = SwiftPMTestProject.defaultPackageManifest,
     workspaces: (URL) -> [WorkspaceFolder] = { [WorkspaceFolder(uri: DocumentURI($0))] },
     build: Bool = false,
+    allowBuildFailure: Bool = false,
     usePullDiagnostics: Bool = true,
     testName: String = #function
   ) async throws {
@@ -66,7 +67,11 @@ public class SwiftPMTestProject: MultiFileTestProject {
     )
 
     if build {
-      try await Self.build(at: self.scratchDirectory)
+      if allowBuildFailure {
+        try? await Self.build(at: self.scratchDirectory)
+      } else {
+        try await Self.build(at: self.scratchDirectory)
+      }
     }
     // Wait for the indexstore-db to finish indexing
     _ = try await testClient.send(PollIndexRequest())

Sources/SKTestSupport/TestSourceKitLSPClient.swift

@@ -362,7 +362,7 @@ public struct DocumentPositions {
     }
   }
 
-  init(markedText: String) {
+  public init(markedText: String) {
     let (markers, textWithoutMarker) = extractMarkers(markedText)
     self.init(markers: markers, textWithoutMarkers: textWithoutMarker)
   }