Fix GITHUB_STEP_SUMMARY size limit exceeded with non-ASCII characters

Directory.Packages.props

@@ -2,7 +2,6 @@
   <PropertyGroup>
     <ManagePackageVersionsCentrally>true</ManagePackageVersionsCentrally>
   </PropertyGroup>
-
   <ItemGroup>
     <PackageVersion Include="coverlet.collector" Version="10.0.0" />
     <PackageVersion Include="CSharpier.MsBuild" Version="1.2.6" />
@@ -12,9 +11,9 @@
     <PackageVersion Include="Microsoft.Testing.Platform" Version="2.2.2" />
     <PackageVersion Include="MSTest" Version="4.2.2" />
     <PackageVersion Include="PolyShim" Version="2.11.0" />
-    <PackageVersion Include="PowerKit" Version="1.1.1" />
+    <PackageVersion Include="PowerKit" Version="1.2.0" />
     <PackageVersion Include="RazorBlade" Version="1.0.0" />
     <PackageVersion Include="xunit" Version="2.9.3" />
     <PackageVersion Include="xunit.runner.visualstudio" Version="3.1.5" />
   </ItemGroup>
-</Project>
+</Project>

GitHubActionsTestLogger.Tests/MtpSummarySpecs.cs

@@ -387,4 +387,66 @@ public async Task I_can_try_to_use_the_logger_to_produce_a_summary_when_the_outp
         testOutput.WriteLine("Summary output:");
         testOutput.WriteLine(summaryOutput);
     }
+
+    [Fact]
+    public async Task I_can_try_to_use_the_logger_to_produce_a_summary_when_the_output_file_is_nearly_full_and_content_contains_non_ascii_characters_and_get_a_truncated_summary_within_the_size_limit()
+    {
+        // Arrange
+        using var testResultsDir = TempDirectory.Create();
+        using var summaryFile = TempFile.Create();
+
+        const int prefillSize = 1024 * 1024 - 250;
+        File.WriteAllZeroes(summaryFile.Path, prefillSize);
+
+        using var commandWriter = new StringWriter();
+
+        // Use a file-backed StreamWriter so that the file path is exposed internally
+        await using var summaryFileStream = File.Open(
+            summaryFile.Path,
+            FileMode.Append,
+            FileAccess.Write,
+            FileShare.ReadWrite
+        );
+
+        await using var summaryWriter = new StreamWriter(summaryFileStream);
+
+        var builder = await TestApplication.CreateBuilderAsync([
+            "--results-directory",
+            testResultsDir.Path,
+            "--report-github",
+            "--report-github-summary-include-passed",
+        ]);
+
+        // Use non-ASCII characters in test names (each Chinese character is 3 bytes in UTF-8,
+        // so truncating by char count instead of byte count would exceed the size limit)
+        builder.RegisterFakeTests(
+            new TestNodeBuilder()
+                .SetDisplayName(new string('一', 100))
+                .SetOutcome(TestOutcome.Failed)
+                .Build(),
+            new TestNodeBuilder()
+                .SetDisplayName(new string('二', 100))
+                .SetOutcome(TestOutcome.Failed)
+                .Build()
+        );
+
+        builder.AddGitHubActionsReporting(commandWriter, summaryWriter);
+
+        // Act
+        var app = await builder.BuildAsync();
+        await app.RunAsync();
+
+        await summaryWriter.FlushAsync();
+
+        // Assert
+        var commandOutput = commandWriter.ToString();
+        var summaryFileSize = new FileInfo(summaryFile.Path).Length;
+
+        commandOutput.Should().ContainAll("::warning", "truncated");
+        summaryFileSize.Should().BeLessThanOrEqualTo(1024 * 1024);
+
+        testOutput.WriteLine($"Summary file size: {summaryFileSize}");
+        testOutput.WriteLine("Command output:");
+        testOutput.WriteLine(commandOutput);
+    }
 }

GitHubActionsTestLogger.Tests/VsTestSummarySpecs.cs

@@ -432,4 +432,65 @@ public async Task I_can_try_to_use_the_logger_to_produce_a_summary_when_the_outp
         testOutput.WriteLine("Summary output:");
         testOutput.WriteLine(summaryOutput);
     }
+
+    [Fact]
+    public async Task I_can_try_to_use_the_logger_to_produce_a_summary_when_the_output_file_is_nearly_full_and_content_contains_non_ascii_characters_and_get_a_truncated_summary_within_the_size_limit()
+    {
+        // Arrange
+        using var summaryFile = TempFile.Create();
+
+        const int prefillSize = 1024 * 1024 - 250;
+        File.WriteAllZeroes(summaryFile.Path, prefillSize);
+
+        using var commandWriter = new StringWriter();
+
+        var events = new FakeTestLoggerEvents();
+        var logger = new VsTestLogger();
+
+        // Use a file-backed StreamWriter so that the file path is exposed internally
+        using var summaryFileStream = File.Open(
+            summaryFile.Path,
+            FileMode.Append,
+            FileAccess.Write,
+            FileShare.ReadWrite
+        );
+
+        using var summaryWriter = new StreamWriter(summaryFileStream);
+
+        logger.Initialize(
+            events,
+            new Dictionary<string, string?> { ["summary-include-passed"] = "true" },
+            commandWriter,
+            summaryWriter
+        );
+
+        // Act
+        // Use non-ASCII characters in test names (each Chinese character is 3 bytes in UTF-8,
+        // so truncating by char count instead of byte count would exceed the size limit)
+        events.SimulateTestRun(
+            new TestResultBuilder()
+                .SetDisplayName(new string('一', 100))
+                .SetFullyQualifiedName("TestProject.SomeTests.Test1")
+                .SetOutcome(TestOutcome.Failed)
+                .Build(),
+            new TestResultBuilder()
+                .SetDisplayName(new string('二', 100))
+                .SetFullyQualifiedName("TestProject.SomeTests.Test2")
+                .SetOutcome(TestOutcome.Failed)
+                .Build()
+        );
+
+        await summaryWriter.FlushAsync();
+
+        // Assert
+        var commandOutput = commandWriter.ToString();
+        var summaryFileSize = new FileInfo(summaryFile.Path).Length;
+
+        commandOutput.Should().ContainAll("::warning", "truncated");
+        summaryFileSize.Should().BeLessThanOrEqualTo(1024 * 1024);
+
+        testOutput.WriteLine($"Summary file size: {summaryFileSize}");
+        testOutput.WriteLine("Command output:");
+        testOutput.WriteLine(commandOutput);
+    }
 }

GitHubActionsTestLogger/GitHub/GitHubWorkflow.cs

@@ -102,28 +102,15 @@ private string TruncateSummary(string content)
             return content;
 
         var existingSize = File.Exists(filePath) ? new FileInfo(filePath).Length : 0L;
-
-        // Calculate required size for the summary content
         var contentSize = Encoding.UTF8.GetByteCount(content);
-        var newLineSize = Encoding.UTF8.GetByteCount(Environment.NewLine);
-        var requiredSize = contentSize + newLineSize * 3;
 
-        if (existingSize + requiredSize > GitHubEnvironment.SummaryFileSizeLimit)
+        if (existingSize + contentSize > GitHubEnvironment.SummaryFileSizeLimit)
         {
             var availableSize = (int)
-                Math.Min(
-                    GitHubEnvironment.SummaryFileSizeLimit - existingSize - newLineSize * 3L,
-                    int.MaxValue
-                );
-
-            return
-                // There is enough space to fit the whole content
-                availableSize > 0
-                && requiredSize <= availableSize
-                    ? content
-                // There is enough space to fit some of the content
-                : availableSize > 0 && requiredSize > availableSize ? content[..availableSize]
-                // There is no space at all
+                Math.Min(GitHubEnvironment.SummaryFileSizeLimit - existingSize, int.MaxValue);
+
+            return availableSize > 0
+                ? content.TruncateBytes(availableSize, Encoding.UTF8)
                 : string.Empty;
         }
 
@@ -132,9 +119,19 @@ private string TruncateSummary(string content)
 
     public async Task CreateSummaryAsync(string content)
     {
+        // If the summary file already contains HTML content, we need to first add two newlines
+        // in order to switch GitHub's parser from HTML mode back to markdown mode.
+        // It's safe to do it unconditionally because, if the file is empty, these newlines
+        // will simply be ignored.
+        // https://github.com/Tyrrrz/GitHubActionsTestLogger/issues/22
+        // The newlines are included in the content before truncation so that the byte budget
+        // is always accurate and the file never exceeds the size limit.
+        var actualContent =
+            Environment.NewLine + Environment.NewLine + content + Environment.NewLine;
+
         // Truncate summary to fit into GitHub's step summary size limit
-        var truncated = TruncateSummary(content);
-        if (truncated.Length < content.Length)
+        var truncatedContent = TruncateSummary(actualContent);
+        if (truncatedContent.Length < actualContent.Length)
         {
             await CreateWarningAnnotationAsync(
                 "Test summary truncated",
@@ -147,15 +144,7 @@ If you have multiple summary providers in the same step (e.g. running multiple t
             );
         }
 
-        // If the summary file already contains HTML content, we need to first add two newlines
-        // in order to switch GitHub's parser from HTML mode back to markdown mode.
-        // It's safe to do it unconditionally because, if the file is empty, these newlines
-        // will simply be ignored.
-        // https://github.com/Tyrrrz/GitHubActionsTestLogger/issues/22
-        await summaryWriter.WriteLineAsync();
-        await summaryWriter.WriteLineAsync();
-
-        await summaryWriter.WriteLineAsync(content);
+        await summaryWriter.WriteAsync(truncatedContent);
         await summaryWriter.FlushAsync();
     }
 }