Retry writing file contents in tests on Windows

Sources/SKTestSupport/String+writeWithRetry.swift

@@ -0,0 +1,42 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2025 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 SKLogging
+
+#if compiler(>=6)
+package import Foundation
+#else
+import Foundation
+#endif
+
+extension String {
+  /// Write this string to the given URL using UTF-8 encoding.
+  ///
+  /// Sometimes file writes fail on Windows because another process (like sourcekitd or clangd) still has exclusive
+  /// access to the file but releases it soon after. Retry to save the file if this happens. This matches what a user
+  /// would do.
+  package func writeWithRetry(to url: URL) async throws {
+    #if os(Windows)
+    try await repeatUntilExpectedResult(timeout: .seconds(10), sleepInterval: .milliseconds(200)) {
+      do {
+        try self.write(to: url, atomically: true, encoding: .utf8)
+        return true
+      } catch {
+        logger.error("Writing file contents to \(url) failed, will retry: \(error.forLogging)")
+        return false
+      }
+    }
+    #else
+    try self.write(to: url, atomically: true, encoding: .utf8)
+    #endif
+  }
+}

Tests/SourceKitLSPTests/BackgroundIndexingTests.swift

@@ -509,15 +509,7 @@ final class BackgroundIndexingTests: XCTestCase {
 
     // clangd might have Header.h open, which prevents us from updating it. Keep retrying until we get a successful
     // write. This matches what a user would do.
-    try await repeatUntilExpectedResult {
-      do {
-        try headerNewMarkedContents.write(to: try XCTUnwrap(uri.fileURL), atomically: true, encoding: .utf8)
-        return true
-      } catch {
-        logger.error("Writing new Header.h failed, will retry: \(error.forLogging)")
-        return false
-      }
-    }
+    try await headerNewMarkedContents.writeWithRetry(to: try XCTUnwrap(uri.fileURL))
 
     project.testClient.send(DidChangeWatchedFilesNotification(changes: [FileEvent(uri: uri, type: .changed)]))
     try await project.testClient.send(PollIndexRequest())
@@ -1254,10 +1246,10 @@ final class BackgroundIndexingTests: XCTestCase {
 
     // Just committing a new version of the dependency shouldn't change anything because we didn't update the package
     // dependencies.
-    try """
+    try await """
     /// Do something v1.1.0
     public func doSomething() {}
-    """.write(to: dependencySwiftURL, atomically: true, encoding: .utf8)
+    """.writeWithRetry(to: dependencySwiftURL)
     try await dependencyProject.tag(changedFiles: [dependencySwiftURL], version: "1.1.0")
 
     let hoverAfterNewVersionCommit = try await project.testClient.send(
@@ -1403,7 +1395,7 @@ final class BackgroundIndexingTests: XCTestCase {
         return value
       }
       """
-    try newLibAContents.write(to: XCTUnwrap(uri.fileURL), atomically: true, encoding: .utf8)
+    try await newLibAContents.writeWithRetry(to: XCTUnwrap(uri.fileURL))
     project.testClient.send(
       DidOpenTextDocumentNotification(
         textDocument: TextDocumentItem(uri: uri, language: .swift, version: 0, text: newLibAContents)
@@ -1590,7 +1582,7 @@ final class BackgroundIndexingTests: XCTestCase {
         }
         """
     )
-    try newAContents.write(to: XCTUnwrap(libAUri.fileURL), atomically: true, encoding: .utf8)
+    try await newAContents.writeWithRetry(to: XCTUnwrap(libAUri.fileURL))
 
     project.testClient.send(
       DidChangeWatchedFilesNotification(changes: [FileEvent(uri: libAUri, type: .changed)])
@@ -1645,11 +1637,11 @@ final class BackgroundIndexingTests: XCTestCase {
     XCTAssertEqual(completionBeforeEdit.items.map(\.label), ["self"])
 
     let libAUri = try project.uri(for: "LibA.swift")
-    try """
+    try await """
     public struct LibA {
       public func test() {}
     }
-    """.write(to: XCTUnwrap(libAUri.fileURL), atomically: true, encoding: .utf8)
+    """.writeWithRetry(to: XCTUnwrap(libAUri.fileURL))
 
     project.testClient.send(
       DidChangeWatchedFilesNotification(changes: [FileEvent(uri: libAUri, type: .changed)])
@@ -1708,7 +1700,7 @@ final class BackgroundIndexingTests: XCTestCase {
     )
 
     let libAUri = try project.uri(for: "LibA.swift")
-    try "public let myVar: Int".write(to: try XCTUnwrap(libAUri.fileURL), atomically: true, encoding: .utf8)
+    try await "public let myVar: Int".writeWithRetry(to: try XCTUnwrap(libAUri.fileURL))
     project.testClient.send(DidChangeWatchedFilesNotification(changes: [FileEvent(uri: libAUri, type: .changed)]))
 
     try await repeatUntilExpectedResult {

Tests/SourceKitLSPTests/CompilationDatabaseTests.swift

@@ -57,7 +57,7 @@ final class CompilationDatabaseTests: XCTestCase {
     // Remove -DFOO from the compile commands.
 
     let compileFlagsUri = try project.uri(for: FixedCompilationDatabaseBuildSystem.dbName)
-    try "".write(to: compileFlagsUri.fileURL!, atomically: false, encoding: .utf8)
+    try await "".writeWithRetry(to: XCTUnwrap(compileFlagsUri.fileURL))
 
     project.testClient.send(
       DidChangeWatchedFilesNotification(changes: [

Tests/SourceKitLSPTests/DefinitionTests.swift

@@ -354,7 +354,7 @@ class DefinitionTests: XCTestCase {
     let (updatedAPositions, updatedACode) = DocumentPositions.extract(from: "func 2️⃣sayHello() {}")
 
     let aUri = try project.uri(for: "FileA.swift")
-    try updatedACode.write(to: try XCTUnwrap(aUri.fileURL), atomically: true, encoding: .utf8)
+    try await updatedACode.writeWithRetry(to: XCTUnwrap(aUri.fileURL))
     project.testClient.send(
       DidChangeWatchedFilesNotification(changes: [FileEvent(uri: aUri, type: .changed)])
     )

Tests/SourceKitLSPTests/DependencyTrackingTests.swift

@@ -98,7 +98,7 @@ final class DependencyTrackingTests: XCTestCase {
 
     // Write an empty header file first since clangd doesn't handle missing header
     // files without a recently upstreamed extension.
-    try "".write(to: generatedHeaderURL, atomically: true, encoding: .utf8)
+    try await "".writeWithRetry(to: generatedHeaderURL)
     let (mainUri, _) = try project.openDocument("main.c")
 
     let openDiags = try await project.testClient.nextDiagnosticsNotification()
@@ -108,7 +108,7 @@ final class DependencyTrackingTests: XCTestCase {
 
     // Update the header file to have the proper contents for our code to build.
     let contents = "int libX(int value);"
-    try contents.write(to: generatedHeaderURL, atomically: true, encoding: .utf8)
+    try await contents.writeWithRetry(to: generatedHeaderURL)
 
     let workspace = try await unwrap(project.testClient.server.workspaceForDocument(uri: mainUri))
     await workspace.filesDependenciesUpdated([mainUri])

Tests/SourceKitLSPTests/LocalClangTests.swift

@@ -332,13 +332,13 @@ final class LocalClangTests: XCTestCase {
     XCTAssert(initialDiags.diagnostics.isEmpty)
 
     // We rename Object to MyObject in the header.
-    try """
+    try await """
     struct MyObject {
       int field;
     };
 
     struct MyObject * newObject();
-    """.write(to: headerUri.fileURL!, atomically: false, encoding: .utf8)
+    """.writeWithRetry(to: XCTUnwrap(headerUri.fileURL))
 
     let clangdServer = await project.testClient.server.languageService(
       for: mainUri,

Tests/SourceKitLSPTests/MainFilesProviderTests.swift

@@ -192,7 +192,7 @@ final class MainFilesProviderTests: XCTestCase {
       #include "\(try project.scratchDirectory.filePath)/Sources/shared.h"
       """
     let fancyLibraryUri = try project.uri(for: "MyFancyLibrary.c")
-    try newFancyLibraryContents.write(to: try XCTUnwrap(fancyLibraryUri.fileURL), atomically: false, encoding: .utf8)
+    try await newFancyLibraryContents.writeWithRetry(to: XCTUnwrap(fancyLibraryUri.fileURL))
     project.testClient.send(
       DidChangeWatchedFilesNotification(changes: [FileEvent(uri: fancyLibraryUri, type: .changed)])
     )

Tests/SourceKitLSPTests/PublishDiagnosticsTests.swift

@@ -148,7 +148,7 @@ final class PublishDiagnosticsTests: XCTestCase {
 
     let updatedACode = "func sayHello() {}"
     let aUri = try project.uri(for: "FileA.swift")
-    try updatedACode.write(to: try XCTUnwrap(aUri.fileURL), atomically: true, encoding: .utf8)
+    try await updatedACode.writeWithRetry(to: XCTUnwrap(aUri.fileURL))
     project.testClient.send(
       DidChangeWatchedFilesNotification(changes: [FileEvent(uri: aUri, type: .changed)])
     )

Tests/SourceKitLSPTests/PullDiagnosticsTests.swift

@@ -198,7 +198,7 @@ final class PullDiagnosticsTests: XCTestCase {
 
     let updatedACode = "func sayHello() {}"
     let aUri = try project.uri(for: "FileA.swift")
-    try updatedACode.write(to: try XCTUnwrap(aUri.fileURL), atomically: true, encoding: .utf8)
+    try await updatedACode.writeWithRetry(to: XCTUnwrap(aUri.fileURL))
     project.testClient.send(
       DidChangeWatchedFilesNotification(changes: [FileEvent(uri: aUri, type: .changed)])
     )

Tests/SourceKitLSPTests/SwiftPMIntegrationTests.swift

@@ -121,7 +121,7 @@ final class SwiftPMIntegrationTests: XCTestCase {
         l.2️⃣foo()
       }
       """
-    try extractMarkers(newFileContents).textWithoutMarkers.write(to: newFileUrl, atomically: false, encoding: .utf8)
+    try await extractMarkers(newFileContents).textWithoutMarkers.writeWithRetry(to: newFileUrl)
 
     // Check that we don't get cross-file code completion before we send a `DidChangeWatchedFilesNotification` to make
     // sure we didn't include the file in the initial retrieval of build settings.

Tests/SourceKitLSPTests/WorkspaceTestDiscoveryTests.swift

@@ -172,7 +172,7 @@ final class WorkspaceTestDiscoveryTests: XCTestCase {
         }6️⃣
         """
     )
-    try newFileContents.write(to: try XCTUnwrap(myTestsUri.fileURL), atomically: true, encoding: .utf8)
+    try await newFileContents.writeWithRetry(to: XCTUnwrap(myTestsUri.fileURL))
     project.testClient.send(DidChangeWatchedFilesNotification(changes: [FileEvent(uri: myTestsUri, type: .changed)]))
 
     let testsAfterDocumentChanged = try await project.testClient.send(WorkspaceTestsRequest())
@@ -672,7 +672,7 @@ final class WorkspaceTestDiscoveryTests: XCTestCase {
       .deletingLastPathComponent()
       .appendingPathComponent("MyNewTests.swift")
     let uri = DocumentURI(url)
-    try fileContents.write(to: url, atomically: true, encoding: .utf8)
+    try await fileContents.writeWithRetry(to: url)
     project.testClient.send(
       DidChangeWatchedFilesNotification(changes: [FileEvent(uri: uri, type: .created)])
     )
@@ -867,7 +867,7 @@ final class WorkspaceTestDiscoveryTests: XCTestCase {
     let testsAfterFileRemove = try await project.testClient.send(WorkspaceTestsRequest())
     XCTAssertEqual(testsAfterFileRemove, [])
 
-    try extractMarkers(markedFileContents).textWithoutMarkers.write(to: myTestsUrl, atomically: true, encoding: .utf8)
+    try await extractMarkers(markedFileContents).textWithoutMarkers.writeWithRetry(to: myTestsUrl)
     project.testClient.send(DidChangeWatchedFilesNotification(changes: [FileEvent(uri: myTestsUri, type: .created)]))
 
     let testsAfterFileReAdded = try await project.testClient.send(WorkspaceTestsRequest())
@@ -935,7 +935,7 @@ final class WorkspaceTestDiscoveryTests: XCTestCase {
 
     let uri = try XCTUnwrap(project.fileURI.fileURL)
 
-    try (originalContents + addedTest).write(to: uri, atomically: true, encoding: .utf8)
+    try await (originalContents + addedTest).writeWithRetry(to: uri)
 
     project.testClient.send(
       DidChangeWatchedFilesNotification(changes: [FileEvent(uri: project.fileURI, type: .changed)])