Hot patch vstest.console to not terminate processes

build/PatchVSTestConsole.ps1

@@ -0,0 +1,18 @@
+# Replaces 'ldc.i4.s 100' with 'ldc.i4.m1, nop' to fix incorrect termination of the test host
+# https://github.com/Microsoft/vstest/issues/1900
+
+$file = Join-Path $PSScriptRoot '..\Tools\dotnetcli\sdk\2.1.503\Microsoft.TestPlatform.CrossPlatEngine.bin';
+$bytes = [System.IO.File]::ReadAllBytes($file);
+If ($bytes[0xE259] -eq 0x15 -and $bytes[0xE25A] -eq 0x00) {
+	# Already patched
+	Exit 0
+}
+
+If ($bytes[0xE259] -ne 0x1F -or $bytes[0xE25A] -ne 0x64) {
+	# Unexpected file
+	Exit 1
+}
+
+$bytes[0xE259] = 0x15;
+$bytes[0xE25A] = 0x00;
+[System.IO.File]::WriteAllBytes($file, $bytes);

build/ci/phase-template.yml

@@ -40,6 +40,9 @@ phases:
     - ${{ if eq(parameters.name, 'MacOS') }}:
       - script: brew update && brew install libomp mono-libgdiplus gettext && brew link gettext --force
         displayName: Install runtime dependencies
+    - powershell: $(Build.SourcesDirectory)/build/PatchVSTestConsole.ps1
+      displayName: Hot patch vstest.console
+      condition: and(succeeded(), eq(variables._codeCoverage, 'true'))
     - script: $(_buildScript) -$(_configuration) -runtests -coverage=$(_codeCoverage)
       displayName: Run Tests.
     - script: $(Build.SourcesDirectory)/Tools/dotnetcli/dotnet msbuild build/Codecoverage.proj /p:CodeCovToken=$(CODECOV_TOKEN)