[fix] Fix CopyTraceDataCollectorArtifacts overwriting newer MTP CodeCoverage DLLs by nohwnd · Pull Request #15794 · microsoft/vstest

nohwnd · 2026-05-17T01:29:46Z

🤖 This is an automated fix generated by the Issue Repro Triage & Auto-Fix agent.

Root Cause

In Microsoft.CodeCoverage.targets, the CopyTraceDataCollectorArtifacts target blindly copies the entire Microsoft.CodeCoverage package payload into the publish directory after ComputeFilesToPublish. When Microsoft.Testing.Extensions.CodeCoverage 18.1.0 is also referenced (e.g. via MSTest.Sdk 4.0.2), it places Microsoft.CodeCoverage.Core v18.1.0.0 into publish output, but this target then overwrites it with the older v18.0.6.0 from Microsoft.CodeCoverage 18.0.1.

At runtime, Microsoft.Testing.Extensions.CodeCoverage expects v18.1.0.0 but finds v18.0.6.0, causing:

System.IO.FileNotFoundException: Could not load file or assembly 'Microsoft.CodeCoverage.Core, Version=18.1.0.0'

Fix

Skip the CopyTraceDataCollectorArtifacts copy when Microsoft.Testing.Extensions.CodeCoverage is directly referenced. That package already provides the correct version of all its artifacts, so the blind copy is both unnecessary and harmful in that scenario.

Change

src/package/Microsoft.CodeCoverage/Microsoft.CodeCoverage.targets — detect Microsoft.Testing.Extensions.CodeCoverage via PackageReference items and skip the copy when present.

🔍 Triaged by Issue Repro Triage & Auto-Fix 🔍

…e DLLs When Microsoft.Testing.Extensions.CodeCoverage is referenced alongside Microsoft.NET.Test.Sdk, the CopyTraceDataCollectorArtifacts target blindly copies older Microsoft.CodeCoverage artifacts into the publish directory, overwriting the newer DLLs from the MTP package. This causes a FileNotFoundException at runtime because the newer version is expected but the older one is present. Fix: Skip the blind copy when Microsoft.Testing.Extensions.CodeCoverage is directly referenced, as that package already provides the correct version of all its artifacts. Fixes #15387 Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

This PR updates the Microsoft.CodeCoverage.targets packaging logic to avoid overwriting newer code coverage binaries during dotnet publish when newer coverage tooling is present, addressing the publish-time assembly version conflict described in #15387.

Changes:

Adds MSBuild logic to detect Microsoft.Testing.Extensions.CodeCoverage and conditionally skip CopyTraceDataCollectorArtifacts.
Updates the target’s inline documentation to explain why the copy is skipped in that scenario.

+    <!-- Detect whether Microsoft.Testing.Extensions.CodeCoverage is directly referenced. -->
    <ItemGroup>
+      <_MtpCodeCoverageRef Include="@(PackageReference)" Condition="'%(PackageReference.Identity)' == 'Microsoft.Testing.Extensions.CodeCoverage'" />



  <!-- This target required to enable /collect:"Code Coverage" in "dotnet publish" scenario with "dotnet vstest".
-       E.g: Release pipelines where user/project nuget cache not available on current machine. -->
+       E.g: Release pipelines where user/project nuget cache not available on current machine.


nohwnd

🧠 Expert Review — PR #15794

Activated dimensions (via src/package/ routing): Dependency & Package Integrity, Build Script & Infrastructure Hygiene, Cross-TFM & Framework Resolution

Critical: Detection logic may miss transitive references

The core fix uses @(PackageReference) to detect whether Microsoft.Testing.Extensions.CodeCoverage is referenced. This only catches direct references in the project file. However, the PR's own motivation describes the scenario where the package arrives transitively via MSTest.Sdk 4.0.2 — which would not be visible in @(PackageReference).

In that scenario, _MtpCodeCoverageRef will be empty, the condition evaluates to ''== '' (true = copy proceeds), and the newer DLLs are still overwritten. The fix would have no effect for the described root cause.

See the inline comment for a concrete suggestion using $(Pkgmicrosoft_Testing_Extensions_CodeCoverage) which NuGet sets for all resolved packages including transitive ones.

Other dimensions: No issues found

Build Script & Infrastructure Hygiene: MSBuild syntax is valid; target ordering (AfterTargets="ComputeFilesToPublish") is appropriate.
Cross-TFM: .targets file is TFM-agnostic; no concerns.
Description alignment: The PR title and description accurately describe the intent. The description is well-written and matches the diff.

🧠 Reviewed by Expert Code Reviewer

🧠 Reviewed by Expert Code Reviewer 🧠

nohwnd · 2026-05-17T01:34:19Z


+    <!-- Detect whether Microsoft.Testing.Extensions.CodeCoverage is directly referenced. -->
    <ItemGroup>
+      <_MtpCodeCoverageRef Include="@(PackageReference)" Condition="'%(PackageReference.Identity)' == 'Microsoft.Testing.Extensions.CodeCoverage'" />


[Dependency & Package Integrity] Transitive references not detected — fix may not work in the described scenario

@(PackageReference) only contains directly declared package references from the project file. Transitive dependencies (packages brought in by other packages) do not appear here.

The PR description motivates the fix with this exact scenario:

When Microsoft.Testing.Extensions.CodeCoverage 18.1.0 is also referenced (e.g. via MSTest.Sdk 4.0.2)...

If a user has MSTest.Sdk as their SDK (or has it as a PackageReference) and Microsoft.Testing.Extensions.CodeCoverage arrives transitively, this detection will see an empty _MtpCodeCoverageRef and still perform the overwrite — exactly the bug being fixed.

A more robust approach would be to check @(ResolvedPackageReference) (populated by RunResolvePackageDependencies) or use the NuGet-generated package path property:

 <_MtpCodeCoverageRef Include="@(PackageReference)" Condition="'%(Identity)' == 'Microsoft.Testing.Extensions.CodeCoverage'" />  <PropertyGroup> <_MtpCodeCoveragePresent Condition="'$(Pkgmicrosoft_Testing_Extensions_CodeCoverage)' != ''">true</_MtpCodeCoveragePresent> </PropertyGroup>

Or, alternatively, check whether a file from the newer package is already present in the publish output (file-based version comparison), though that is more complex.

At minimum, the condition should also cover '$(Pkgmicrosoft_Testing_Extensions_CodeCoverage)' != '', as NuGet sets this property for all resolved packages (direct and transitive).

Good catch. This was addressed in the follow-up commit f0d0102 — the condition now also checks $(Pkgmicrosoft_Testing_Extensions_CodeCoverage), which NuGet sets for all resolved packages including transitive ones:

<_MtpCodeCoveragePresent Condition="'@(_MtpCodeCoverageRef)' != '' or '$(Pkgmicrosoft_Testing_Extensions_CodeCoverage)' != ''">true</_MtpCodeCoveragePresent>

This covers the MSTest.Sdk transitive scenario described in the PR.

🔧 Iterated by PR Iteration Agent 🔧

🔧 Iterated by PR Iteration Agent 🔧

… reference Use $(Pkgmicrosoft_Testing_Extensions_CodeCoverage) in addition to @(PackageReference) to detect when Microsoft.Testing.Extensions.CodeCoverage is present transitively (e.g. via MSTest.Sdk). NuGet sets the Pkg* property for all resolved packages, including transitive ones. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

nohwnd · 2026-05-17T01:39:23Z

Commit pushed: f0d0102

🔧 Iterated by PR Iteration Agent 🔧

Youssef1313 · 2026-05-17T05:26:44Z

+    </ItemGroup>
+
+    <PropertyGroup>
+      <_MtpCodeCoveragePresent Condition="'@(_MtpCodeCoverageRef)' != '' or '$(Pkgmicrosoft_Testing_Extensions_CodeCoverage)' != ''">true</_MtpCodeCoveragePresent>


It sounds weird to have property conditioned on an item.

Also sounds weird to have two ways for checking the package reference.

I'm also not sure if the overall fix is even correct. This won't handle if CC is brought transitively.

Youssef1313 · 2026-05-17T05:29:40Z

    </ItemGroup>

-    <Copy SourceFiles="@(TraceDataCollectorArtifacts)" DestinationFolder="$(PublishDir)%(RecursiveDir)" />
+    <Copy SourceFiles="@(TraceDataCollectorArtifacts)" DestinationFolder="$(PublishDir)%(RecursiveDir)"


I would say this copy invocation should skip any existing files in destination (regardless of whether or not they are different).

I'm also not even sure why the whole target is needed. Maybe if you track the original problem it tries to solve, you can find a whole better solution.

nohwnd · 2026-05-29T15:25:33Z

needs more careful analysis.

…f MTP detection Replace the Microsoft.Testing.Extensions.CodeCoverage detection logic with Overwrite="false" on the Copy task. This is simpler and more robust: - Files already placed by MTP CodeCoverage (which runs before this target) are not overwritten with older versions from this package. - All TraceDataCollector-specific files are still copied for users without MTP. - No package detection logic needed (avoids Pkgxxx reliability concerns). The previous detection-based approach also had a gap: it skipped copying *all* files, including TraceDataCollector-specific ones that MTP doesn't provide, which could silently break /collect:"Code Coverage" for MSTest.Sdk users. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

nohwnd · 2026-05-29T15:52:41Z

Commit pushed: c264ce4

🔧 Iterated by PR Iteration Agent 🔧

nohwnd · 2026-05-29T15:52:44Z

Implemented the Overwrite="false" approach as analyzed in my previous comment.

What changed:

Removed the Microsoft.Testing.Extensions.CodeCoverage detection logic (_MtpCodeCoverageRef, _MtpCodeCoveragePresent, Pkgmicrosoft_Testing_Extensions_CodeCoverage checks)
Added Overwrite="false" to the Copy task
All TraceDataCollectorArtifacts are always copied, but files already present (placed by MTP CodeCoverage) are not overwritten

This is simpler and addresses both concerns from the analysis:

✅ MTP's newer DLLs won't be overwritten by older MC files
✅ TraceDataCollector-specific files (not provided by MTP) are still copied, so /collect:"Code Coverage" works for MSTest.Sdk users too

🔧 Iterated by PR Iteration Agent 🔧

Copilot

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 1 comment.

+       Uses Overwrite="false" so that files already placed by Microsoft.Testing.Extensions.CodeCoverage
+       (which runs before this target) are not overwritten with older versions from this package. -->
  <Target Name="CopyTraceDataCollectorArtifacts" AfterTargets="ComputeFilesToPublish">

    <ItemGroup>
      <TraceDataCollectorArtifacts Include="$(MSBuildThisFileDirectory)\**\*.*" />
    </ItemGroup>

-    <Copy SourceFiles="@(TraceDataCollectorArtifacts)" DestinationFolder="$(PublishDir)%(RecursiveDir)" />
+    <Copy SourceFiles="@(TraceDataCollectorArtifacts)" DestinationFolder="$(PublishDir)%(RecursiveDir)"
+          Overwrite="false" />


nohwnd

🧠 Expert Review — PR #15794

The Overwrite="false" approach is a clean, robust fix. It works regardless of MSBuild target execution order between this package and Microsoft.Testing.Extensions.CodeCoverage (as long as MTP uses the default Overwrite=true), so the fix is more reliable than the previous PackageReference-detection approach.

No blocking issues found. One inline note on the code comment's accuracy and a minor observation about incremental publish behavior.

🧠 Reviewed by Expert Code Reviewer 🧠

🧠 Reviewed by Expert Code Reviewer 🧠

nohwnd · 2026-05-29T16:04:39Z

  <!-- This target required to enable /collect:"Code Coverage" in "dotnet publish" scenario with "dotnet vstest".
-       E.g: Release pipelines where user/project nuget cache not available on current machine. -->
+       E.g: Release pipelines where user/project nuget cache not available on current machine.
+       Uses Overwrite="false" so that files already placed by Microsoft.Testing.Extensions.CodeCoverage


The comment says the fix works because MTP CodeCoverage "runs before this target," but the fix is actually ordering-independent:

MTP first: newer files land, this target skips them (Overwrite=false) ✓

This target first: older files land, MTP then overwrites with newer (default Overwrite=true) ✓

The fix is correct either way, but the comment may mislead future readers into thinking a specific execution order is required. Consider rewording to:



Also worth noting: with Overwrite="false", incremental re-publishes to a non-clean output directory will not refresh stale DLLs from this package. This is generally fine for CI scenarios where publish targets a clean directory, but may be surprising in local dev incremental publishes.

Updated the comment to clarify the fix is ordering-independent:



🔧 Iterated by PR Iteration Agent 🔧

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

nohwnd · 2026-05-29T16:20:37Z

Commit pushed: 64869a6

🔧 Iterated by PR Iteration Agent 🔧

Copilot AI review requested due to automatic review settings May 17, 2026 01:29

nohwnd added the Area: Code Coverage label May 17, 2026

Copilot started reviewing on behalf of nohwnd May 17, 2026 01:30 View session

Copilot AI reviewed May 17, 2026

View reviewed changes

nohwnd commented May 17, 2026

View reviewed changes

This comment has been minimized.

Sign in to view

nohwnd mentioned this pull request May 17, 2026

Daily Maintenance Digest — 2026-05-17 #15768

Closed

Youssef1313 reviewed May 17, 2026

View reviewed changes

This was referenced May 18, 2026

Daily Maintenance Digest — 2026-05-20 #16036

Closed

Daily Maintenance Digest — 2026-05-25 #16049

Closed

nohwnd mentioned this pull request May 26, 2026

Daily Maintenance Digest — 2026-06-01 #16066

Open

This comment has been minimized.

Sign in to view

Copilot AI review requested due to automatic review settings May 29, 2026 15:52

Copilot started reviewing on behalf of nohwnd May 29, 2026 15:52 View session

Copilot AI reviewed May 29, 2026

View reviewed changes

nohwnd commented May 29, 2026

View reviewed changes

fix: clarify Overwrite=false comment is ordering-independent

64869a6

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

nohwnd mentioned this pull request May 29, 2026

[aw] Expert Code Reviewer 🧠 failed #16075

Open

Conversation

nohwnd commented May 17, 2026

Root Cause

Fix

Change

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

nohwnd left a comment

Choose a reason for hiding this comment

🧠 Expert Review — PR #15794

Critical: Detection logic may miss transitive references

Other dimensions: No issues found

Uh oh!

nohwnd May 17, 2026

Choose a reason for hiding this comment

Uh oh!

nohwnd May 17, 2026

Choose a reason for hiding this comment

Uh oh!

This comment has been minimized.

nohwnd commented May 17, 2026

Uh oh!

Youssef1313 May 17, 2026

Choose a reason for hiding this comment

Uh oh!

Youssef1313 May 17, 2026

Choose a reason for hiding this comment

Uh oh!

nohwnd commented May 29, 2026

Uh oh!

This comment has been minimized.

nohwnd commented May 29, 2026

Uh oh!

nohwnd commented May 29, 2026

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

nohwnd left a comment

Choose a reason for hiding this comment

🧠 Expert Review — PR #15794

Uh oh!

nohwnd May 29, 2026

Choose a reason for hiding this comment

Uh oh!

nohwnd May 29, 2026

Choose a reason for hiding this comment

Uh oh!

nohwnd commented May 29, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants