chore: import upstream snapshot with attribution

dotnet/eng/verify-samples/CsvResultWriter.cs

@@ -0,0 +1,56 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System.Text;
+
+namespace VerifySamples;
+
+/// <summary>
+/// Writes a CSV summary of sample verification results.
+/// </summary>
+internal static class CsvResultWriter
+{
+    /// <summary>
+    /// Writes the results to a CSV file at the specified path.
+    /// </summary>
+    public static async Task WriteAsync(
+        string path,
+        IReadOnlyList<VerificationResult> orderedResults,
+        IReadOnlyList<(string Name, string Reason)> skipped,
+        IReadOnlyList<SampleDefinition> samples)
+    {
+        var pathLookup = samples.ToDictionary(s => s.Name, s => s.ProjectPath);
+
+        var sb = new StringBuilder();
+        sb.AppendLine("Sample,ProjectPath,Status,FailedChecks,Failures");
+
+        foreach (var result in orderedResults)
+        {
+            var status = result.Passed ? "PASSED" : "FAILED";
+            var failedChecks = result.Failures.Count;
+            var failures = string.Join("; ", result.Failures);
+            pathLookup.TryGetValue(result.SampleName, out var projectPath);
+            sb.AppendLine($"{CsvEscape(result.SampleName)},{CsvEscape(projectPath ?? "")},{status},{failedChecks},{CsvEscape(failures)}");
+        }
+
+        foreach (var (name, reason) in skipped)
+        {
+            pathLookup.TryGetValue(name, out var projectPath);
+            sb.AppendLine($"{CsvEscape(name)},{CsvEscape(projectPath ?? "")},SKIPPED,0,{CsvEscape(reason)}");
+        }
+
+        await File.WriteAllTextAsync(path, sb.ToString());
+    }
+
+    /// <summary>
+    /// Escapes a value for CSV: wraps in quotes if it contains commas, quotes, or newlines.
+    /// </summary>
+    private static string CsvEscape(string value)
+    {
+        if (value.Contains('"') || value.Contains(',') || value.Contains('\n') || value.Contains('\r'))
+        {
+            return $"\"{value.Replace("\"", "\"\"")}\"";
+        }
+
+        return value;
+    }
+}