Build tests on Linux and Windows (#47106)

Author: NikolaMilosavljevic

eng/pipelines/templates/stages/vmr-build.yml

@@ -364,7 +364,7 @@ stages:
 
     - template: ../jobs/vmr-build.yml
       parameters:
-        buildName: ${{ format('{0}_Ubuntu', variables.ubuntuName) }}
+        buildName: ${{ format('{0}_Ubuntu_BuildTests', variables.ubuntuName) }}
         isBuiltFromVmr: ${{ parameters.isBuiltFromVmr }}
         vmrBranch: ${{ variables.VmrBranch }}
         pool: ${{ parameters.pool_Linux }}
@@ -373,17 +373,19 @@ stages:
           image: ${{ variables.ubuntuContainerImage }}
         targetOS: linux
         targetArchitecture: x64
-
-    - template: ../jobs/vmr-build.yml
-      parameters:
-        buildName: Windows_BuildTests
-        isBuiltFromVmr: ${{ parameters.isBuiltFromVmr }}
-        vmrBranch: ${{ variables.VmrBranch }}
-        pool: ${{ parameters.pool_Windows }}
-        targetOS: windows
-        targetArchitecture: x64
         extraProperties: /p:DotNetBuildTests=true
 
+    - ${{ if ne(variables['Build.Reason'], 'PullRequest') }}:
+      - template: ../jobs/vmr-build.yml
+        parameters:
+          buildName: Windows_BuildTests
+          isBuiltFromVmr: ${{ parameters.isBuiltFromVmr }}
+          vmrBranch: ${{ variables.VmrBranch }}
+          pool: ${{ parameters.pool_Windows }}
+          targetOS: windows
+          targetArchitecture: x64
+          extraProperties: /p:DotNetBuildTests=true
+
 #### VERTICAL BUILD (Official) ####
 - ${{ if not(parameters.isSourceOnlyBuild) }}:
   - stage: VMR_Vertical_Build

src/SourceBuild/content/repo-projects/sdk.proj

@@ -3,6 +3,9 @@
   <PropertyGroup>
     <LogVerbosityOptOut>true</LogVerbosityOptOut>
 
+    <!-- Tests are only building on Windows - https://github.com/dotnet/source-build/issues/4882 -->
+    <DotNetBuildTestsOptOut Condition="'$(OS)' != 'Windows_NT'">true</DotNetBuildTestsOptOut>
+
     <BuildArgs Condition="'$(TargetOS)' == 'windows'">$(BuildArgs) -nativeToolsOnMachine</BuildArgs>
     <BuildArgs>$(BuildArgs) /p:PackageProjectUrl=https://github.com/dotnet/sdk</BuildArgs>
     <BuildArgs>$(BuildArgs) /p:PortableRid=$(PortableRid)</BuildArgs>