Add infrastructure to define indexed single-file workspaces inside the tests

Package.swift

@@ -224,7 +224,7 @@ let package = Package(
         "LSPLogging",
         "SKCore",
         .product(name: "SwiftPM-auto", package: "swift-package-manager"),
-        .product(name: "SwiftToolsSupport-auto", package: "swift-tools-support-core")
+        .product(name: "SwiftToolsSupport-auto", package: "swift-tools-support-core"),
       ],
       exclude: ["CMakeLists.txt"]
     ),
@@ -245,6 +245,7 @@ let package = Package(
       dependencies: [
         "CSKTestSupport",
         "LSPTestSupport",
+        "SKCore",
         "SourceKitLSP",
         .product(name: "ISDBTestSupport", package: "indexstore-db"),
         .product(name: "SwiftToolsSupport-auto", package: "swift-tools-support-core"),

Sources/LanguageServerProtocol/Requests/PollIndexRequest.swift

@@ -18,4 +18,6 @@
 public struct PollIndexRequest: RequestType {
   public static var method: String = "workspace/_pollIndex"
   public typealias Response = VoidResponse
+
+  public init() {}
 }

Sources/SKTestSupport/IndexedSingleSwiftFileWorkspace.swift

@@ -0,0 +1,97 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2022 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 ISDBTibs
+import LanguageServerProtocol
+import SKCore
+import SourceKitLSP
+import TSCBasic
+
+public struct IndexedSingleSwiftFileWorkspace {
+  enum Error: Swift.Error {
+    case swiftcNotFound
+  }
+
+  public let testClient: TestSourceKitLSPClient
+  public let fileURI: DocumentURI
+  public let positions: DocumentPositions
+
+  public init(
+    _ markedText: String,
+    testName: String = #function
+  ) async throws {
+    let testWorkspaceDirectory = try testScratchDir(testName: testName)
+
+    let testFileURL = testWorkspaceDirectory.appendingPathComponent("test.swift")
+    let indexURL = testWorkspaceDirectory.appendingPathComponent("index")
+    let indexDBURL = testWorkspaceDirectory.appendingPathComponent("index-db")
+    guard let swiftc = ToolchainRegistry.shared.default?.swiftc?.asURL else {
+      throw Error.swiftcNotFound
+    }
+
+    // Create workspace with source file and compile_commands.json
+
+    try extractMarkers(markedText).textWithoutMarkers.write(to: testFileURL, atomically: false, encoding: .utf8)
+
+    var compilerArguments: [String] = [
+      testFileURL.path,
+      "-index-store-path", indexURL.path,
+      "-index-ignore-system-modules",
+      "-o", testWorkspaceDirectory.appendingPathComponent("test.o").path,
+    ]
+    if let sdk = TibsBuilder.defaultSDKPath {
+      compilerArguments += ["-sdk", sdk]
+    }
+
+    let compilationDatabase = JSONCompilationDatabase(
+      [
+        JSONCompilationDatabase.Command(
+          directory: testWorkspaceDirectory.path,
+          filename: testFileURL.path,
+          commandLine: [swiftc.path] + compilerArguments
+        )
+      ]
+    )
+    let encoder = JSONEncoder()
+    encoder.outputFormatting = .prettyPrinted
+    try encoder.encode(compilationDatabase).write(
+      to: testWorkspaceDirectory.appendingPathComponent("compile_commands.json")
+    )
+
+    // Run swiftc to build the index store
+    try await Process.checkNonZeroExit(arguments: [swiftc.path] + compilerArguments)
+
+    // Create the test client
+    var options = SourceKitServer.Options.testDefault
+    options.indexOptions = IndexOptions(
+      indexStorePath: try AbsolutePath(validating: indexURL.path),
+      indexDatabasePath: try AbsolutePath(validating: indexDBURL.path)
+    )
+    self.testClient = try await TestSourceKitLSPClient(
+      serverOptions: options,
+      workspaceFolders: [
+        WorkspaceFolder(uri: DocumentURI(testWorkspaceDirectory))
+      ],
+      cleanUp: {
+        try? FileManager.default.removeItem(at: testWorkspaceDirectory)
+      }
+    )
+
+    // Wait for the indexstore-db to finish indexing
+    _ = try await testClient.send(PollIndexRequest())
+
+    // Open the document
+    self.fileURI = DocumentURI(testFileURL)
+    self.positions = testClient.openDocument(markedText, uri: fileURI)
+  }
+}