Drop codecov.io upload; publish coverage to Azure DevOps instead

testfx already collects coverage with Microsoft Code Coverage (MTP `--coverage`
configured by `test/coverage.config`). The only codecov.io-specific bits were
the upload step and dashboard publishing — replace them with an AzDO-native
publish that surfaces coverage in the build's Code Coverage tab and on the
build summary (one click from the GitHub PR status check).

Changes:

* Remove `codecov.yml` and the `Codecov` NuGet package reference.
* Delete `eng/CodeCoverage.proj` outright — its only remaining job was a
  `dotnet coverage merge` invocation, which is now a one-line YAML script
  step. The unit/integration split it used to do was a codecov.io flag thing
  and has no equivalent in `PublishCodeCoverageResults@2`.
* Replace the "Upload coverage to codecov.io" pipeline step with a "Merge
  coverage to Cobertura" script (one line, invokes the `dotnet-coverage`
  local tool already declared in `.config/dotnet-tools.json`) plus
  `PublishCodeCoverageResults@2`, which renders Cobertura natively in
  Azure DevOps.
* Update the matching comment in `eng/pipelines/steps/test-non-windows.yml`.

Reviewers no longer get a Codecov PR comment; coverage is one click away on the
AzDO build (linked from the GitHub PR status check). Same path as dotnet/runtime,
dotnet/sdk, etc.

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

Author: Evangelink

Directory.Packages.props

@@ -65,7 +65,6 @@
     <PackageVersion Include="System.Threading.Tasks.Extensions" Version="$(SystemThreadingTasksExtensionsVersion)" />
   </ItemGroup>
   <ItemGroup Label="Test dependencies">
-    <PackageVersion Include="Codecov" Version="1.12.3" />
     <PackageVersion Include="AwesomeAssertions" Version="9.4.0" />
     <PackageVersion Include="FSharp.Core" Version="11.0.100" />
     <PackageVersion Include="NUnit" Version="4.6.0" />

azure-pipelines.yml

@@ -130,8 +130,9 @@ stages:
           #     ValidateTestHostEnvironmentVariablesAsync hard-fails the run on non-NETCoreApp hosts
           #     (see src/Platform/Microsoft.Testing.Extensions.CrashDump/CrashDumpEnvironmentVariableProvider.cs),
           #     and this glob mixes net4x and net8+/net9+ hosts.
-          #   --coverage — Codecov upload is Debug-only (see "Upload coverage to codecov.io" step
-          #     below), so collecting coverage in Release would just write unused .coverage files.
+          #   --coverage — coverage upload is Debug-only (see "Merge coverage" / "Publish coverage to
+          #     Azure DevOps" steps below), so collecting coverage in Release would just write unused
+          #     .coverage files.
           - script: dotnet test --no-build --test-modules "artifacts/bin/*UnitTests*/$(_BuildConfig)/**/*UnitTests.exe" --results-directory $(BUILD.SOURCESDIRECTORY)\artifacts\TestResults\$(_BuildConfig) --no-progress --output detailed --report-trx --report-trx-filename "{asm}_{tfm}.trx" --report-azdo --report-azdo-progress --report-azdo-summary --report-junit --report-junit-filename "{asm}_{tfm}.xml" --hangdump --hangdump-timeout 15m --diagnostic --diagnostic-output-directory $(BUILD.SOURCESDIRECTORY)\artifacts\log\$(_BuildConfig) --diagnostic-verbosity trace
             name: TestRelease
             displayName: Test (unit tests only)
@@ -160,14 +161,28 @@ stages:
               ArtifactName: Integration_Tests_Windows_Binlogs_$(_BuildConfig)
             condition: and(always(), eq(variables._BuildConfig, 'Debug'))
 
-          # Upload code coverage to codecov.io
-          - script: dotnet msbuild -restore
-              eng/CodeCoverage.proj
-              /p:Configuration=$(_BuildConfig)
-              /bl:$(BUILD.SOURCESDIRECTORY)\artifacts\log\$(_BuildConfig)\CodeCoverage.binlog
-            displayName: Upload coverage to codecov.io
+          # Merge per-test-module .coverage files (Microsoft Code Coverage, collected via MTP
+          # --coverage configured by test/coverage.config) into a single Cobertura.xml. We invoke
+          # dotnet-coverage (declared as a local tool in .config/dotnet-tools.json) directly — the
+          # tool is restored as part of the build above.
+          - script: dotnet coverage merge
+              --output $(BUILD.SOURCESDIRECTORY)\artifacts\coverage\Cobertura.xml
+              --output-format Cobertura
+              $(BUILD.SOURCESDIRECTORY)\artifacts\TestResults\$(_BuildConfig)\*.coverage
+            displayName: Merge coverage to Cobertura
             condition: and(succeeded(), eq(variables._BuildConfig, 'Debug'))
 
+          # Publish the merged Cobertura report to Azure DevOps. Coverage shows up in the build's
+          # "Code Coverage" tab and on the build summary; the GitHub PR status check links back to
+          # this build, so reviewers can click through to see coverage without a third-party
+          # dashboard (we used to upload to codecov.io here).
+          - task: PublishCodeCoverageResults@2
+            displayName: 'Publish coverage to Azure DevOps'
+            inputs:
+              summaryFileLocation: '$(Build.SourcesDirectory)/artifacts/coverage/Cobertura.xml'
+              pathToSources: '$(Build.SourcesDirectory)/src'
+            condition: and(succeededOrFailed(), eq(variables._BuildConfig, 'Debug'))
+
           - task: PublishBuildArtifacts@1
             displayName: 'Publish local dumps'
             inputs:

codecov.yml

@@ -47,8 +47,9 @@ steps:
 #     ValidateTestHostEnvironmentVariablesAsync hard-fails the run on non-NETCoreApp hosts
 #     (see src/Platform/Microsoft.Testing.Extensions.CrashDump/CrashDumpEnvironmentVariableProvider.cs).
 #     Skipped here too for cross-platform parity with the Windows script (mixed net4x+netcoreapp glob).
-#   --coverage — Codecov upload is Debug-only (see "Upload coverage to codecov.io" step
-#     in azure-pipelines.yml), so collecting coverage in Release would just write unused .coverage files.
+#   --coverage — coverage upload is Debug-only (see "Merge coverage" / "Publish coverage to
+#     Azure DevOps" steps in azure-pipelines.yml), so collecting coverage in Release would just
+#     write unused .coverage files.
 - script: dotnet test --no-build --test-modules "artifacts/bin/*UnitTests*/$(_BuildConfig)/**/*UnitTests.dll" --results-directory $(BUILD.SOURCESDIRECTORY)/artifacts/TestResults/$(_BuildConfig) --no-progress --output detailed --report-trx --report-trx-filename "{asm}_{tfm}.trx" --report-azdo --report-azdo-progress --report-azdo-summary --report-junit --report-junit-filename "{asm}_{tfm}.xml" --hangdump --hangdump-timeout 15m --diagnostic --diagnostic-output-directory $(BUILD.SOURCESDIRECTORY)/artifacts/log/$(_BuildConfig) --diagnostic-verbosity trace
   name: TestRelease
   displayName: Test (unit tests only)