TestsReportGenerator: Always show the error message, and truncate only the stdout

tests/Aspire.Hosting.Tests/DistributedApplicationTests.cs

@@ -367,6 +367,7 @@ public Task AfterEndpointsAllocatedAsync(DistributedApplicationModel appModel, C
     }
 
     [Fact]
+    [QuarantinedTest("https://github.com/dotnet/aspire/issues/9340")]
     public async Task TestServicesWithMultipleReplicas()
     {
         var replicaCount = 3;

tests/Aspire.Hosting.Yarp.Tests/YarpFunctionalTests.cs

@@ -11,6 +11,7 @@ public class YarpFunctionalTests(ITestOutputHelper testOutputHelper)
 {
     [Fact]
     [RequiresDocker]
+    [QuarantinedTest("https://github.com/dotnet/aspire/issues/9344")]
     public async Task VerifyYarpResource()
     {
         var cts = new CancellationTokenSource(TimeSpan.FromMinutes(5));

tools/GenerateTestSummary/TestSummaryGenerator.cs

@@ -144,21 +144,31 @@ public static void CreateSingleTestSummaryReport(string trxFilePath, StringBuild
 
                 """);
 
-                var errorMsgBuilder = new StringBuilder();
-                errorMsgBuilder.AppendLine(test.Output?.ErrorInfo?.InnerText ?? string.Empty);
+                reportBuilder.AppendLine();
+                reportBuilder.AppendLine("```yml");
+
+                reportBuilder.AppendLine(test.Output?.ErrorInfo?.InnerText);
                 if (test.Output?.StdOut is not null)
                 {
-                    errorMsgBuilder.AppendLine();
-                    errorMsgBuilder.AppendLine("### StdOut");
-                    errorMsgBuilder.AppendLine(test.Output.StdOut);
+                    const int halfLength = 25_000;
+                    var stdOutSpan = test.Output.StdOut.AsSpan();
+
+                    reportBuilder.AppendLine();
+                    reportBuilder.AppendLine("### StdOut");
+
+                    var startSpan = stdOutSpan[..Math.Min(halfLength, stdOutSpan.Length)];
+                    reportBuilder.AppendLine(startSpan.ToString());
+
+                    if (stdOutSpan.Length > halfLength)
+                    {
+                        reportBuilder.AppendLine(CultureInfo.InvariantCulture, $"{Environment.NewLine}... (snip) ...{Environment.NewLine}");
+                        var endSpan = stdOutSpan[^halfLength..];
+                        // `endSpan` might not begin at the true beginning of the original line
+                        reportBuilder.Append("... ");
+                        reportBuilder.Append(endSpan);
+                    }
                 }
 
-                // Truncate long error messages for readability
-                var errorMsgTruncated = TruncateTheStart(errorMsgBuilder.ToString(), 50_000);
-
-                reportBuilder.AppendLine();
-                reportBuilder.AppendLine("```yml");
-                reportBuilder.AppendLine(errorMsgTruncated);
                 reportBuilder.AppendLine("```");
                 reportBuilder.AppendLine();
                 reportBuilder.AppendLine("</div>");
@@ -181,9 +191,4 @@ public static string GetTestTitle(string trxFileName)
 
     [GeneratedRegex(@"(?<testName>.*)_(?<tfm>net\d+\.0)_.*")]
     private static partial Regex TestNameFromTrxFileNameRegex();
-
-    private static string? TruncateTheStart(string? s, int maxLength)
-        => s is null || s.Length <= maxLength
-            ? s
-            : "... (truncated) " + s[^maxLength..];
 }