Add test cases for the request reducer

Author: ahoppen

Package.swift

@@ -54,14 +54,16 @@ let package = Package(
       dependencies: []
     ),
 
-    // MARK: Csourcekitd:
+    // MARK: Csourcekitd
     // C modules wrapper for sourcekitd.
     .target(
       name: "Csourcekitd",
       dependencies: [],
       exclude: ["CMakeLists.txt"]
     ),
 
+    // MARK: Diagnose
+
     .target(
       name: "Diagnose",
       dependencies: [
@@ -75,6 +77,19 @@ let package = Package(
       exclude: ["CMakeLists.txt"]
     ),
 
+    .testTarget(
+      name: "DiagnoseTests",
+      dependencies: [
+        "Diagnose",
+        "LSPLogging",
+        "LSPTestSupport",
+        "SourceKitD",
+        "SKCore",
+        "SKTestSupport",
+        .product(name: "SwiftToolsSupport-auto", package: "swift-tools-support-core"),
+      ]
+    ),
+
     // MARK: LanguageServerProtocol
     // The core LSP types, suitable for any LSP implementation.
     .target(

Sources/Diagnose/CMakeLists.txt

@@ -6,6 +6,7 @@ add_library(Diagnose STATIC
   ReductionError.swift
   ReproducerBundle.swift
   RequestInfo.swift
+  SourceKitD+RunWithYaml.swift
   SourceKitDRequestExecutor.swift
   SourcekitdRequestCommand.swift
   SourceReducer.swift)

Sources/Diagnose/DiagnoseCommand.swift

@@ -128,7 +128,7 @@ public struct DiagnoseCommand: AsyncParsableCommand {
       nspredicate = NSPredicate(format: predicate)
     }
     #endif
-    let executor = SourceKitRequestExecutor(
+    let executor = OutOfProcessSourceKitRequestExecutor(
       sourcekitd: URL(fileURLWithPath: sourcekitd),
       reproducerPredicate: nspredicate
     )

Sources/Diagnose/RequestInfo.swift

@@ -14,7 +14,8 @@ import Foundation
 import RegexBuilder
 
 /// All the information necessary to replay a sourcektid request.
-struct RequestInfo {
+@_spi(Testing)
+public struct RequestInfo {
   /// The JSON request object. Contains the following dynamic placeholders:
   ///  - `$OFFSET`: To be replaced by `offset` before running the request
   ///  - `$FILE`: Will be replaced with a path to the file that contains the reduced source code.
@@ -26,10 +27,12 @@ struct RequestInfo {
   var offset: Int
 
   /// The compiler arguments of the request. Replaces the `$COMPILER_ARGS`placeholder in the request template.
-  var compilerArgs: [String]
+  @_spi(Testing)
+  public var compilerArgs: [String]
 
   /// The contents of the file that the sourcekitd request operates on.
-  var fileContents: String
+  @_spi(Testing)
+  public var fileContents: String
 
   func request(for file: URL) throws -> String {
     let encoder = JSONEncoder()
@@ -47,7 +50,8 @@ struct RequestInfo {
 
   }
 
-  init(requestTemplate: String, offset: Int, compilerArgs: [String], fileContents: String) {
+  @_spi(Testing)
+  public init(requestTemplate: String, offset: Int, compilerArgs: [String], fileContents: String) {
     self.requestTemplate = requestTemplate
     self.offset = offset
     self.compilerArgs = compilerArgs
@@ -57,7 +61,8 @@ struct RequestInfo {
   /// Creates `RequestInfo` from the contents of the JSON sourcekitd request at `requestPath`.
   ///
   /// The contents of the source file are read from disk.
-  init(request: String) throws {
+  @_spi(Testing)
+  public init(request: String) throws {
     var requestTemplate = request
 
     // Extract offset

Sources/Diagnose/SourceKitD+RunWithYaml.swift

@@ -0,0 +1,35 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// 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 SourceKitD
+
+extension SourceKitD {
+  /// Parse the request from YAML and execute it.
+  @_spi(Testing)
+  public func run(requestYaml: String) async throws -> SKDResponse {
+    let request = try requestYaml.cString(using: .utf8)?.withUnsafeBufferPointer { buffer in
+      var error: UnsafeMutablePointer<CChar>?
+      let req = api.request_create_from_yaml(buffer.baseAddress, &error)
+      if let error {
+        throw ReductionError("Failed to parse sourcekitd request from YAML: \(String(cString: error))")
+      }
+      precondition(req != nil)
+      return req
+    }
+    return await withCheckedContinuation { continuation in
+      var handle: sourcekitd_request_handle_t? = nil
+      api.send_request(request, &handle) { resp in
+        continuation.resume(returning: SKDResponse(resp, sourcekitd: self))
+      }
+    }
+  }
+}

Sources/Diagnose/SourceKitDRequestExecutor.swift

@@ -17,7 +17,8 @@ import struct TSCBasic.AbsolutePath
 import class TSCBasic.Process
 
 /// The different states in which a sourcekitd request can finish.
-enum SourceKitDRequestResult {
+@_spi(Testing)
+public enum SourceKitDRequestResult {
   /// The request succeeded.
   case success(response: String)
 
@@ -41,8 +42,14 @@ fileprivate extension String {
   }
 }
 
+/// An executor that can run a sourcekitd request and indicate whether the request reprodes a specified issue.
+@_spi(Testing)
+public protocol SourceKitRequestExecutor {
+  func run(request requestString: String) async throws -> SourceKitDRequestResult
+}
+
 /// Runs `sourcekit-lsp run-sourcekitd-request` to check if a sourcekit-request crashes.
-struct SourceKitRequestExecutor {
+struct OutOfProcessSourceKitRequestExecutor: SourceKitRequestExecutor {
   /// The path to `sourcekitd.framework/sourcekitd`.
   private let sourcekitd: URL
 

Sources/Diagnose/SourceReducer.swift

@@ -18,7 +18,8 @@ import SwiftSyntax
 // MARK: - Entry point
 
 extension RequestInfo {
-  func reduceInputFile(using executor: SourceKitRequestExecutor) async throws -> RequestInfo {
+  @_spi(Testing)
+  public func reduceInputFile(using executor: SourceKitRequestExecutor) async throws -> RequestInfo {
     let reducer = SourceReducer(sourcekitdExecutor: executor)
     return try await reducer.run(initialRequestInfo: self)
   }
@@ -156,7 +157,7 @@ fileprivate class SourceReducer {
       fileContents: reducedSource
     )
 
-    try reducedSource.write(to: temporarySourceFile, atomically: false, encoding: .utf8)
+    try reducedSource.write(to: temporarySourceFile, atomically: true, encoding: .utf8)
     let result = try await sourcekitdExecutor.run(request: reducedRequestInfo.request(for: temporarySourceFile))
     if case .reproducesIssue = result {
       logSuccessfulReduction(reducedRequestInfo)

Sources/Diagnose/SourcekitdRequestCommand.swift

@@ -39,26 +39,8 @@ public struct SourceKitdRequestCommand: AsyncParsableCommand {
 
   public func run() async throws {
     let requestString = try String(contentsOf: URL(fileURLWithPath: sourcekitdRequestPath))
-
-    let sourcekitd = try SourceKitDImpl.getOrCreate(
-      dylibPath: try! AbsolutePath(validating: sourcekitdPath)
-    )
-
-    let request = try requestString.cString(using: .utf8)?.withUnsafeBufferPointer { buffer in
-      var error: UnsafeMutablePointer<CChar>?
-      let req = sourcekitd.api.request_create_from_yaml(buffer.baseAddress, &error)
-      if let error {
-        throw ReductionError("Failed to parse sourcekitd request from JSON: \(String(cString: error))")
-      }
-      precondition(req != nil)
-      return req
-    }
-    let response: SKDResponse = await withCheckedContinuation { continuation in
-      var handle: sourcekitd_request_handle_t? = nil
-      sourcekitd.api.send_request(request, &handle) { resp in
-        continuation.resume(returning: SKDResponse(resp, sourcekitd: sourcekitd))
-      }
-    }
+    let sourcekitd = try SourceKitDImpl.getOrCreate(dylibPath: try! AbsolutePath(validating: sourcekitdPath))
+    let response = try await sourcekitd.run(requestYaml: requestString)
 
     switch response.error {
     case .requestFailed, .requestInvalid, .requestCancelled, .missingRequiredSymbol: