[test-improver] Add unit tests for ArtifactPostProcessingHelper.IsReparsePoint

[github-actions]

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Goal and rationale

ArtifactPostProcessingHelper.IsReparsePoint (in src/Platform/SharedExtensionHelpers/) is a security-relevant helper used by TrxArtifactPostProcessor and HtmlArtifactPostProcessor to refuse writing artifacts through symlinks/reparse points. It had zero direct test coverage.

Approach

The type is compiled once per report-engine assembly (<Compile Include>-linked into TrxReport, HtmlReport, JUnitReport, CtrfReport), so it can't be referenced by name directly from the test project (ambiguous, CS0433). Following the existing ReportFileNameSanitizationConsistencyTests.cs pattern, the new tests resolve IsReparsePoint via reflection anchored on the Trx engine assembly and exercise it with real filesystem operations (no mocking needed):

• Regular directory → false
• Non-existent path → true (fails closed on the exception path)
• Symbolic link to a directory → true (skips with Assert.Inconclusive if the sandbox doesn't permit symlink creation)
• Plain file → false

Coverage impact

New file: test/UnitTests/Microsoft.Testing.Extensions.UnitTests/ArtifactPostProcessingHelperTests.cs (4 tests). ArtifactPostProcessingHelper line coverage for the Trx engine assembly goes from 0% to fully covered by these tests.

Trade-offs

Minimal maintenance burden: tests use only real filesystem operations and no mocks. The reflection indirection mirrors an existing repo pattern for this class of shared, multi-assembly-linked helper.

Reproducibility

./build.sh
dotnet run --project test/UnitTests/Microsoft.Testing.Extensions.UnitTests -f net9.0 --no-build -c Debug -- --filter "FullyQualifiedName~ArtifactPostProcessingHelperTests"

Test Status

• Build: succeeded (Debug, net8.0/net9.0)
• New tests: 4/4 passed
• Full Microsoft.Testing.Extensions.UnitTests suite: 1129 passed, 0 failed, 34 skipped (no regressions)
• dotnet format whitespace --verify-no-changes: clean

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Show patch preview (128 of 128 lines)

From c1c8df0575dc316510b0bc168214a4ed130a9c58 Mon Sep 17 00:00:00 2001
X-GH-AW-Base-Commit: a7f34662ebd9292b2f25750eb0ba8339dd107ad1
From: "github-actions[bot]" <github-actions[bot]@users.noreply.github.com>
Date: Mon, 24 Aug 2026 23:16:37 +0000
Subject: [PATCH] Add unit tests for
 ArtifactPostProcessingHelper.IsReparsePoint

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 .../ArtifactPostProcessingHelperTests.cs      | 105 ++++++++++++++++++
 1 file changed, 105 insertions(+)
 create mode 100644 test/UnitTests/Microsoft.Testing.Extensions.UnitTests/ArtifactPostProcessingHelperTests.cs

diff --git a/test/UnitTests/Microsoft.Testing.Extensions.UnitTests/ArtifactPostProcessingHelperTests.cs b/test/UnitTests/Microsoft.Testing.Extensions.UnitTests/ArtifactPostProcessingHelperTests.cs
new file mode 100644
index 0000000..1250d52
--- /dev/null
+++ b/test/UnitTests/Microsoft.Testing.Extensions.UnitTests/ArtifactPostProcessingHelperTests.cs
@@ -0,0 +1,105 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System.Reflection;
+
+using Microsoft.Testing.Extensions.TrxReport.Abstractions;
+
+namespace Microsoft.Testing.Extensions.UnitTests;
+
+[TestClass]
+public class ArtifactPostProcessingHelperTests
+{
+    // ArtifactPostProcessingHelper is an internal type that is *linked* (compiled) into every
+    // artifact-post-processing engine assembly (Trx, Html, JUnit, Ctrf), so referencing it by name
+    // directly is ambiguous (CS0433). Resolve the method via reflection, anchoring on one public
+    // type from the Trx engine assembly, mirroring ReportFileNameSanitizationConsistencyTests.
+    private static readonly MethodInfo IsReparsePointMethod =
+        (typeof(TrxReportEngine).Assembly.GetType("Microsoft.Testing.Extensions.ArtifactPostProcessingHelper")
+            ?? throw new InvalidOperationException("Could not find
... (truncated)