diff --git a/Sources/LanguageServerProtocol/CMakeLists.txt b/Sources/LanguageServerProtocol/CMakeLists.txt
index 66eafe3fc..47fb86fde 100644
--- a/Sources/LanguageServerProtocol/CMakeLists.txt
+++ b/Sources/LanguageServerProtocol/CMakeLists.txt
@@ -50,6 +50,7 @@ add_library(LanguageServerProtocol STATIC
   Requests/DocumentSemanticTokensRangeRequest.swift
   Requests/DocumentSemanticTokensRequest.swift
   Requests/DocumentSymbolRequest.swift
+  Requests/DocumentTestsRequest.swift
   Requests/ExecuteCommandRequest.swift
   Requests/FoldingRangeRequest.swift
   Requests/FormattingRequests.swift
@@ -86,6 +87,7 @@ add_library(LanguageServerProtocol STATIC
   Requests/WorkspaceSemanticTokensRefreshRequest.swift
   Requests/WorkspaceSymbolResolveRequest.swift
   Requests/WorkspaceSymbolsRequest.swift
+  Requests/WorkspaceTestsRequest.swift
 
   SupportTypes/CallHierarchyItem.swift
   SupportTypes/ClientCapabilities.swift
diff --git a/Sources/LanguageServerProtocol/Messages.swift b/Sources/LanguageServerProtocol/Messages.swift
index 8776ebc24..4c8e54862 100644
--- a/Sources/LanguageServerProtocol/Messages.swift
+++ b/Sources/LanguageServerProtocol/Messages.swift
@@ -45,6 +45,7 @@ public let builtinRequests: [_RequestType.Type] = [
   DocumentSemanticTokensRangeRequest.self,
   DocumentSemanticTokensRequest.self,
   DocumentSymbolRequest.self,
+  DocumentTestsRequest.self,
   ExecuteCommandRequest.self,
   FoldingRangeRequest.self,
   HoverRequest.self,
@@ -82,6 +83,7 @@ public let builtinRequests: [_RequestType.Type] = [
   WorkspaceSemanticTokensRefreshRequest.self,
   WorkspaceSymbolResolveRequest.self,
   WorkspaceSymbolsRequest.self,
+  WorkspaceTestsRequest.self,
 ]
 
 /// The set of known notifications.
diff --git a/Sources/LanguageServerProtocol/Requests/DocumentTestsRequest.swift b/Sources/LanguageServerProtocol/Requests/DocumentTestsRequest.swift
new file mode 100644
index 000000000..598976de8
--- /dev/null
+++ b/Sources/LanguageServerProtocol/Requests/DocumentTestsRequest.swift
@@ -0,0 +1,25 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2023 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
+//
+//===----------------------------------------------------------------------===//
+
+/// A request that returns symbols for all the test classes and test methods within a file.
+///
+/// **(LSP Extension)**
+public struct DocumentTestsRequest: TextDocumentRequest, Hashable {
+  public static let method: String = "document/tests"
+  public typealias Response = [WorkspaceSymbolItem]?
+
+  public var textDocument: TextDocumentIdentifier
+
+  public init(textDocument: TextDocumentIdentifier) {
+    self.textDocument = textDocument
+  }
+}
diff --git a/Sources/LanguageServerProtocol/Requests/WorkspaceTestsRequest.swift b/Sources/LanguageServerProtocol/Requests/WorkspaceTestsRequest.swift
new file mode 100644
index 000000000..e0f2ae311
--- /dev/null
+++ b/Sources/LanguageServerProtocol/Requests/WorkspaceTestsRequest.swift
@@ -0,0 +1,21 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2023 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
+//
+//===----------------------------------------------------------------------===//
+
+/// A request that returns symbols for all the test classes and test methods within the current workspace.
+///
+/// **(LSP Extension)**
+public struct WorkspaceTestsRequest: RequestType, Hashable {
+  public static let method: String = "workspace/tests"
+  public typealias Response = [WorkspaceSymbolItem]?
+
+  public init() {}
+}
diff --git a/Sources/SKCore/BuildSystemManager.swift b/Sources/SKCore/BuildSystemManager.swift
index 39ef3ee33..7dea053ca 100644
--- a/Sources/SKCore/BuildSystemManager.swift
+++ b/Sources/SKCore/BuildSystemManager.swift
@@ -268,7 +268,7 @@ extension BuildSystemManager: MainFilesDelegate {
   /// For Swift or normal C files, this will be the file itself. For header
   /// files, we pick a main file that includes the header since header files
   /// don't have build settings by themselves.
-  private func mainFile(for uri: DocumentURI, language: Language, useCache: Bool = true) async -> DocumentURI {
+  public func mainFile(for uri: DocumentURI, language: Language, useCache: Bool = true) async -> DocumentURI {
     if language == .swift {
       // Swift doesn't have main files. Skip the main file provider query.
       return uri
diff --git a/Sources/SKTestSupport/SwiftPMTestWorkspace.swift b/Sources/SKTestSupport/SwiftPMTestWorkspace.swift
index ac6f82ddd..281607f35 100644
--- a/Sources/SKTestSupport/SwiftPMTestWorkspace.swift
+++ b/Sources/SKTestSupport/SwiftPMTestWorkspace.swift
@@ -45,13 +45,15 @@ public class SwiftPMTestWorkspace: MultiFileTestWorkspace {
     var filesByPath: [RelativeFileLocation: String] = [:]
     for (fileLocation, contents) in files {
       let directories =
-        if fileLocation.directories.isEmpty {
+        switch fileLocation.directories.first {
+        case "Sources", "Tests":
+          fileLocation.directories
+        case nil:
           ["Sources", "MyLibrary"]
-        } else if fileLocation.directories.first != "Sources" {
+        default:
           ["Sources"] + fileLocation.directories
-        } else {
-          fileLocation.directories
         }
+
       filesByPath[RelativeFileLocation(directories: directories, fileLocation.fileName)] = contents
     }
     filesByPath["Package.swift"] = manifest
@@ -77,6 +79,7 @@ public class SwiftPMTestWorkspace: MultiFileTestWorkspace {
       swift.path,
       "build",
       "--package-path", path.path,
+      "--build-tests",
       "-Xswiftc", "-index-ignore-system-modules",
       "-Xcc", "-index-ignore-system-symbols",
     ]
diff --git a/Sources/SourceKitLSP/CMakeLists.txt b/Sources/SourceKitLSP/CMakeLists.txt
index f94e395f0..14fa58ac5 100644
--- a/Sources/SourceKitLSP/CMakeLists.txt
+++ b/Sources/SourceKitLSP/CMakeLists.txt
@@ -7,8 +7,9 @@ add_library(SourceKitLSP STATIC
   Sequence+AsyncMap.swift
   SourceKitIndexDelegate.swift
   SourceKitLSPCommandMetadata.swift
-  SourceKitServer+Options.swift
   SourceKitServer.swift
+  SourceKitServer+Options.swift
+  TestDiscovery.swift
   ToolchainLanguageServer.swift
   Workspace.swift
 )
diff --git a/Sources/SourceKitLSP/SourceKitServer.swift b/Sources/SourceKitLSP/SourceKitServer.swift
index a6fe6a275..dd9cf32e1 100644
--- a/Sources/SourceKitLSP/SourceKitServer.swift
+++ b/Sources/SourceKitLSP/SourceKitServer.swift
@@ -163,7 +163,7 @@ final actor WorkDoneProgressState {
 fileprivate enum TaskMetadata: DependencyTracker {
   /// A task that changes the global configuration of sourcekit-lsp in any way.
   ///
-  /// No other tasks must execute simulateneously with this task since they
+  /// No other tasks must execute simultaneously with this task since they
   /// might be relying on this task to take effect.
   case globalConfigurationChange
 
@@ -336,6 +336,8 @@ fileprivate enum TaskMetadata: DependencyTracker {
       self = .freestanding
     case is WorkspaceSymbolsRequest:
       self = .freestanding
+    case is WorkspaceTestsRequest:
+      self = .freestanding
     default:
       logger.error(
         """
@@ -382,7 +384,7 @@ public actor SourceKitServer {
 
   var languageServices: [LanguageServerType: [ToolchainLanguageServer]] = [:]
 
-  private let documentManager = DocumentManager()
+  let documentManager = DocumentManager()
 
   private var packageLoadingWorkDoneProgress = WorkDoneProgressState(
     "SourceKitLSP.SourceKitServer.reloadPackage",
@@ -398,7 +400,7 @@ public actor SourceKitServer {
   /// Must only be accessed from `queue`.
   private var uriToWorkspaceCache: [DocumentURI: WeakWorkspace] = [:]
 
-  private var workspaces: [Workspace] = [] {
+  private(set) var workspaces: [Workspace] = [] {
     didSet {
       uriToWorkspaceCache = [:]
     }
@@ -837,6 +839,10 @@ extension SourceKitServer: MessageHandler {
       await request.reply { try await shutdown(request.params) }
     case let request as RequestAndReply<WorkspaceSymbolsRequest>:
       await request.reply { try await workspaceSymbols(request.params) }
+    case let request as RequestAndReply<WorkspaceTestsRequest>:
+      await request.reply { try await workspaceTests(request.params) }
+    case let request as RequestAndReply<DocumentTestsRequest>:
+      await self.handleRequest(for: request, requestHandler: self.documentTests)
     case let request as RequestAndReply<PollIndexRequest>:
       await request.reply { try await pollIndex(request.params) }
     case let request as RequestAndReply<BarrierRequest>:
@@ -1499,7 +1505,7 @@ extension SourceKitServer {
     guard matching.count >= minWorkspaceSymbolPatternLength else {
       return []
     }
-    var symbolOccurenceResults: [SymbolOccurrence] = []
+    var symbolOccurrenceResults: [SymbolOccurrence] = []
     for workspace in workspaces {
       workspace.index?.forEachCanonicalSymbolOccurrence(
         containing: matching,
@@ -1511,45 +1517,22 @@ extension SourceKitServer {
         guard !symbol.location.isSystem && !symbol.roles.contains(.accessorOf) else {
           return true
         }
-        symbolOccurenceResults.append(symbol)
+        symbolOccurrenceResults.append(symbol)
         // FIXME: Once we have cancellation support, we should fetch all results and take the top
         // `maxWorkspaceSymbolResults` symbols but bail if cancelled.
         //
         // Until then, take the first `maxWorkspaceSymbolResults` symbols to limit the impact of
         // queries which match many symbols.
-        return symbolOccurenceResults.count < maxWorkspaceSymbolResults
+        return symbolOccurrenceResults.count < maxWorkspaceSymbolResults
       }
     }
-    return symbolOccurenceResults
+    return symbolOccurrenceResults
   }
 
   /// Handle a workspace/symbol request, returning the SymbolInformation.
   /// - returns: An array with SymbolInformation for each matching symbol in the workspace.
   func workspaceSymbols(_ req: WorkspaceSymbolsRequest) async throws -> [WorkspaceSymbolItem]? {
-    let symbols = findWorkspaceSymbols(
-      matching: req.query
-    ).map({ symbolOccurrence -> WorkspaceSymbolItem in
-      let symbolPosition = Position(
-        line: symbolOccurrence.location.line - 1,  // 1-based -> 0-based
-        // FIXME: we need to convert the utf8/utf16 column, which may require reading the file!
-        utf16index: symbolOccurrence.location.utf8Column - 1
-      )
-
-      let symbolLocation = Location(
-        uri: DocumentURI(URL(fileURLWithPath: symbolOccurrence.location.path)),
-        range: Range(symbolPosition)
-      )
-
-      return .symbolInformation(
-        SymbolInformation(
-          name: symbolOccurrence.symbol.name,
-          kind: symbolOccurrence.symbol.kind.asLspSymbolKind(),
-          deprecated: nil,
-          location: symbolLocation,
-          containerName: symbolOccurrence.getContainerName()
-        )
-      )
-    })
+    let symbols = findWorkspaceSymbols(matching: req.query).map(WorkspaceSymbolItem.init)
     return symbols
   }
 
@@ -2294,3 +2277,28 @@ fileprivate func transitiveSubtypeClosure(ofUsrs usrs: [String], index: IndexSto
   }
   return result
 }
+
+extension WorkspaceSymbolItem {
+  init(_ symbolOccurrence: SymbolOccurrence) {
+    let symbolPosition = Position(
+      line: symbolOccurrence.location.line - 1,  // 1-based -> 0-based
+      // FIXME: we need to convert the utf8/utf16 column, which may require reading the file!
+      utf16index: symbolOccurrence.location.utf8Column - 1
+    )
+
+    let symbolLocation = Location(
+      uri: DocumentURI(URL(fileURLWithPath: symbolOccurrence.location.path)),
+      range: Range(symbolPosition)
+    )
+
+    self = .symbolInformation(
+      SymbolInformation(
+        name: symbolOccurrence.symbol.name,
+        kind: symbolOccurrence.symbol.kind.asLspSymbolKind(),
+        deprecated: nil,
+        location: symbolLocation,
+        containerName: symbolOccurrence.getContainerName()
+      )
+    )
+  }
+}
diff --git a/Sources/SourceKitLSP/TestDiscovery.swift b/Sources/SourceKitLSP/TestDiscovery.swift
new file mode 100644
index 000000000..17e065c41
--- /dev/null
+++ b/Sources/SourceKitLSP/TestDiscovery.swift
@@ -0,0 +1,61 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2020 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 IndexStoreDB
+import LanguageServerProtocol
+
+fileprivate extension SymbolOccurrence {
+  /// Assuming that this is a symbol occurrence returned by the index, return whether it can constitute the definition
+  /// of a test case.
+  ///
+  /// The primary intention for this is to filter out references to test cases and extension declarations of test cases.
+  /// The latter is important to filter so we don't include extension declarations for the derived `DiscoveredTests`
+  /// files on non-Darwin platforms.
+  var canBeTestDefinition: Bool {
+    guard roles.contains(.definition) else {
+      return false
+    }
+    guard symbol.kind == .class || symbol.kind == .instanceMethod else {
+      return false
+    }
+    return true
+  }
+}
+
+extension SourceKitServer {
+  func workspaceTests(_ req: WorkspaceTestsRequest) async throws -> [WorkspaceSymbolItem]? {
+    let testSymbols = workspaces.flatMap { (workspace) -> [SymbolOccurrence] in
+      return workspace.index?.unitTests() ?? []
+    }
+    return
+      testSymbols
+      .filter { $0.canBeTestDefinition }
+      .map(WorkspaceSymbolItem.init)
+  }
+
+  func documentTests(
+    _ req: DocumentTestsRequest,
+    workspace: Workspace,
+    languageService: ToolchainLanguageServer
+  ) async throws -> [WorkspaceSymbolItem]? {
+    let snapshot = try self.documentManager.latestSnapshot(req.textDocument.uri)
+    let mainFileUri = await workspace.buildSystemManager.mainFile(
+      for: req.textDocument.uri,
+      language: snapshot.language
+    )
+    let testSymbols = workspace.index?.unitTests(referencedByMainFiles: [mainFileUri.pseudoPath]) ?? []
+    return
+      testSymbols
+      .filter { $0.canBeTestDefinition }
+      .map(WorkspaceSymbolItem.init)
+  }
+}
diff --git a/Tests/SourceKitLSPTests/TestDiscoveryTests.swift b/Tests/SourceKitLSPTests/TestDiscoveryTests.swift
new file mode 100644
index 000000000..22c28f3cc
--- /dev/null
+++ b/Tests/SourceKitLSPTests/TestDiscoveryTests.swift
@@ -0,0 +1,139 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2023 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 LanguageServerProtocol
+import SKTestSupport
+import XCTest
+
+final class TestDiscoveryTests: XCTestCase {
+  func testWorkspaceTests() async throws {
+    try XCTSkipIf(longTestsDisabled)
+
+    let ws = try await SwiftPMTestWorkspace(
+      files: [
+        "Tests/MyLibraryTests/MyTests.swift": """
+        import XCTest
+
+        class 1️⃣MyTests: XCTestCase {
+          func 2️⃣testMyLibrary() {}
+          func unrelatedFunc() {}
+          var testVariable: Int = 0
+        }
+        """
+      ],
+      manifest: """
+        // swift-tools-version: 5.7
+
+        import PackageDescription
+
+        let package = Package(
+          name: "MyLibrary",
+          targets: [.testTarget(name: "MyLibraryTests")]
+        )
+        """,
+      build: true
+    )
+
+    let tests = try await ws.testClient.send(WorkspaceTestsRequest())
+    XCTAssertEqual(
+      tests,
+      [
+        WorkspaceSymbolItem.symbolInformation(
+          SymbolInformation(
+            name: "MyTests",
+            kind: .class,
+            location: Location(
+              uri: try ws.uri(for: "MyTests.swift"),
+              range: Range(try ws.position(of: "1️⃣", in: "MyTests.swift"))
+            )
+          )
+        ),
+        WorkspaceSymbolItem.symbolInformation(
+          SymbolInformation(
+            name: "testMyLibrary()",
+            kind: .method,
+            location: Location(
+              uri: try ws.uri(for: "MyTests.swift"),
+              range: Range(try ws.position(of: "2️⃣", in: "MyTests.swift"))
+            ),
+            containerName: "MyTests"
+          )
+        ),
+      ]
+    )
+  }
+
+  func testDocumentTests() async throws {
+    try XCTSkipIf(longTestsDisabled)
+
+    let ws = try await SwiftPMTestWorkspace(
+      files: [
+        "Tests/MyLibraryTests/MyTests.swift": """
+        import XCTest
+
+        class 1️⃣MyTests: XCTestCase {
+          func 2️⃣testMyLibrary() {}
+          func unrelatedFunc() {}
+          var testVariable: Int = 0
+        }
+        """,
+        "Tests/MyLibraryTests/MoreTests.swift": """
+        import XCTest
+
+        class MoreTests: XCTestCase {
+          func testSomeMore() {}
+        }
+        """,
+      ],
+      manifest: """
+        // swift-tools-version: 5.7
+
+        import PackageDescription
+
+        let package = Package(
+          name: "MyLibrary",
+          targets: [.testTarget(name: "MyLibraryTests")]
+        )
+        """,
+      build: true
+    )
+
+    let (uri, positions) = try ws.openDocument("MyTests.swift")
+    let tests = try await ws.testClient.send(DocumentTestsRequest(textDocument: TextDocumentIdentifier(uri)))
+    XCTAssertEqual(
+      tests,
+      [
+        WorkspaceSymbolItem.symbolInformation(
+          SymbolInformation(
+            name: "MyTests",
+            kind: .class,
+            location: Location(
+              uri: uri,
+              range: Range(positions["1️⃣"])
+            )
+          )
+        ),
+        WorkspaceSymbolItem.symbolInformation(
+          SymbolInformation(
+            name: "testMyLibrary()",
+            kind: .method,
+            location: Location(
+              uri: try ws.uri(for: "MyTests.swift"),
+              range: Range(positions["2️⃣"])
+            ),
+            containerName: "MyTests"
+          )
+        ),
+      ]
+    )
+  }
+}