Fix

Author: tmat

src/BuiltInTools/dotnet-watch/HotReloadDotNetWatcher.cs

@@ -611,8 +611,7 @@ private bool AcceptChange(ChangedPath change)
                 return false;
             }
 
-            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows) &&
-                PathUtilities.GetContainingDirectories(path).FirstOrDefault(IsHiddenWindowsPath) is { } containingHiddenDir)
+            if (PathUtilities.GetContainingDirectories(path).FirstOrDefault(IsHiddenDirectory) is { } containingHiddenDir)
             {
                 Context.Reporter.Report(MessageDescriptor.IgnoringChangeInHiddenDirectory, containingHiddenDir, kind, path);
                 return false;
@@ -621,15 +620,20 @@ private bool AcceptChange(ChangedPath change)
             return true;
         }
 
-        private static bool IsHiddenWindowsPath(string path)
-            // Note: the device root directory on Windows has hidden attribute:
-            => File.GetAttributes(path).HasFlag(FileAttributes.Hidden) && Path.GetDirectoryName(path) != null;
-
-        internal static string FormatTimestamp(DateTime time)
-            => time.ToString("HH:mm:ss.fffffff");
+        // Directory name starts with '.' on Unix is considered hidden.
+        // Apply the same convention on Windows as well (instead of checking for hidden attribute).
+        // This is consistent with SDK rules for default item exclusions:
+        // https://github.com/dotnet/sdk/blob/124be385f90f2c305dde2b817cb470e4d11d2d6b/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.Sdk.DefaultItems.targets#L42
+        private static bool IsHiddenDirectory(string dir)
+            => Path.GetFileName(dir).StartsWith('.');
 
         private static IReadOnlySet<string> GetProjectOutputDirectories(ProjectGraph projectGraph)
         {
+            // TODO: https://github.com/dotnet/sdk/issues/45539
+            // Consider evaluating DefaultItemExcludes and DefaultExcludesInProjectFolder msbuild properties using
+            // https://github.com/dotnet/msbuild/blob/37eb419ad2c986ac5530292e6ee08e962390249e/src/Build/Globbing/MSBuildGlob.cs
+            // to determine which directories should be excluded.
+
             var projectOutputDirectories = new HashSet<string>(PathUtilities.OSSpecificPathComparer);
 
             foreach (var projectNode in projectGraph.ProjectNodes)

src/BuiltInTools/dotnet-watch/Properties/launchSettings.json

@@ -3,7 +3,7 @@
     "dotnet-watch": {
       "commandName": "Project",
       "commandLineArgs": "--verbose /bl:DotnetRun.binlog",
-      "workingDirectory": "C:\\sdk1\\artifacts\\tmp\\Debug\\RenameDirecto---333D0BB9\\AppWithDeps",
+      "workingDirectory": "$(RepoRoot)src\\Assets\\TestProjects\\BlazorWasmWithLibrary\\blazorwasm",
       "environmentVariables": {
         "DOTNET_WATCH_DEBUG_SDK_DIRECTORY": "$(RepoRoot)artifacts\\bin\\redist\\$(Configuration)\\dotnet\\sdk\\$(Version)",
         "DCP_IDE_REQUEST_TIMEOUT_SECONDS": "100000",

test/dotnet-watch.Tests/HotReload/ApplyDeltaTests.cs

@@ -428,7 +428,11 @@ public async Task Razor_Component_ScopedCssAndStaticAssets()
             App.Process.ClearOutput();
         }
 
-        [PlatformSpecificFact(TestPlatforms.Windows | TestPlatforms.OSX)]
+        /// <summary>
+        /// Currently only works on Windows.
+        /// Add TestPlatforms.OSX once https://github.com/dotnet/sdk/issues/45521 is fixed.
+        /// </summary>
+        [PlatformSpecificFact(TestPlatforms.Windows)]
         public async Task MauiBlazor()
         {
             var testAsset = TestAssets.CopyTestAsset("WatchMauiBlazor")

test/dotnet-watch.Tests/HotReload/RuntimeProcessLauncherTests.cs

@@ -533,40 +533,38 @@ public enum DirectoryKind
         Obj,
     }
 
-    [PlatformSpecificTheory(TestPlatforms.Windows)]
-    [CombinatorialData]
-    public Task IgnoredChange_Windows(bool isExisting, bool isIncluded, DirectoryKind directoryKind)
-        => IgnoredChange(isExisting, isIncluded, directoryKind);
-
-    [PlatformSpecificTheory(TestPlatforms.AnyUnix)]
+    [Theory]
     [CombinatorialData]
-    public Task IgnoredChange_Unix(
+    public async Task IgnoredChange(
         bool isExisting,
         bool isIncluded,
-        [CombinatorialValues(DirectoryKind.Obj, DirectoryKind.Bin, DirectoryKind.Ordinary)] DirectoryKind directoryKind)
-        => IgnoredChange(isExisting, isIncluded, directoryKind);
-
-    private async Task IgnoredChange(bool isExisting, bool isIncluded, DirectoryKind directoryKind)
+        [CombinatorialValues] DirectoryKind directoryKind)
     {
         var testAsset = CopyTestAsset("WatchNoDepsApp", [isExisting, isIncluded, directoryKind]);
 
         var workingDirectory = testAsset.Path;
+        string dir;
 
-        var objDir = Path.Combine(workingDirectory, "obj", "Debug", ToolsetInfo.CurrentTargetFramework);
-        var binDir = Path.Combine(workingDirectory, "bin", "Debug", ToolsetInfo.CurrentTargetFramework);
+        switch (directoryKind)
+        {
+            case DirectoryKind.Bin:
+                dir = Path.Combine(workingDirectory, "bin", "Debug", ToolsetInfo.CurrentTargetFramework);
+                break;
 
-        var hiddenDir = Path.Combine(workingDirectory, "hidden");
-        Directory.CreateDirectory(hiddenDir);
-        File.SetAttributes(hiddenDir, FileAttributes.Hidden | FileAttributes.Directory);
+            case DirectoryKind.Obj:
+                dir = Path.Combine(workingDirectory, "obj", "Debug", ToolsetInfo.CurrentTargetFramework);
+                break;
+
+            case DirectoryKind.Hidden:
+                dir = Path.Combine(workingDirectory, ".dir");
+                break;
+
+            default:
+                dir = workingDirectory;
+                break;
+        }
 
         var extension = isIncluded ? ".cs" : ".txt";
-        var dir = directoryKind switch
-        {
-            DirectoryKind.Bin => binDir,
-            DirectoryKind.Obj => objDir,
-            DirectoryKind.Hidden => hiddenDir,
-            _ => workingDirectory,
-        };
 
         Directory.CreateDirectory(dir);
 
@@ -576,7 +574,7 @@ private async Task IgnoredChange(bool isExisting, bool isIncluded, DirectoryKind
         {
             File.WriteAllText(path, "class C { int F() => 1; }");
 
-            if (isIncluded && directoryKind is DirectoryKind.Bin or DirectoryKind.Obj)
+            if (isIncluded && directoryKind is DirectoryKind.Bin or DirectoryKind.Obj or DirectoryKind.Hidden)
             {
                 var project = Path.Combine(workingDirectory, "WatchNoDepsApp.csproj");
                 File.WriteAllText(project, File.ReadAllText(project).Replace(

test/dotnet-watch.Tests/Watch/Utilities/DotNetWatchTestBase.cs

@@ -29,14 +29,11 @@ public void Log(string message)
     public void UpdateSourceFile(string path, string text)
     {
         WriteAllText(path, text);
-        Log($"File '{path}' updated ({HotReloadDotNetWatcher.FormatTimestamp(File.GetLastWriteTimeUtc(path))}).");
+        Log($"File '{path}' updated.");
     }
 
     public void UpdateSourceFile(string path, Func<string, string> contentTransform)
-    {
-        WriteAllText(path, contentTransform(File.ReadAllText(path, Encoding.UTF8)));
-        Log($"File '{path}' updated.");
-    }
+        => UpdateSourceFile(path, contentTransform(File.ReadAllText(path, Encoding.UTF8)));
 
     /// <summary>
     /// Replacement for <see cref="File.WriteAllText"/>, which fails to write to hidden file