Add BuildTestsOnly property to reduce disk space usage

Co-authored-by: radical <[email protected]>

Author: Copilot

.github/workflows/specialized-test-runner.yml

@@ -36,14 +36,16 @@ jobs:
     steps:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
 
-      # We need to build the whole solution, so that we can interrogate each test project
+      # We need to build test projects, so that we can interrogate each test project
       # and find out whether it contains any tests of the specified type.
+      # We use BuildTestsOnly=true to reduce disk space usage by skipping src, playground, and pack projects.
       - name: Build the solution
         run: >
           ./build.sh
           --restore
           --build
           -c Release
+          /p:BuildTestsOnly=true
           /p:GeneratePackageOnBuild=false
           ${{ !inputs.enablePlaywrightInstall && '/p:InstallBrowsersForPlaywright=false' || '' }}
 

eng/Build.props

@@ -7,7 +7,10 @@
     <TargetRids Condition="'$(TargetRids)' == ''">$(BuildRid)</TargetRids>
   </PropertyGroup>
 
-  <ItemGroup Condition="'$(SkipManagedBuild)' != 'true'">
+  <!-- `$(BuildTestsOnly)` allows building only test projects, skipping src, playground,
+        and pack projects. This is useful for reducing disk space usage when only test
+        projects need to be built, such as during test runsheet generation. -->
+  <ItemGroup Condition="'$(SkipManagedBuild)' != 'true' and '$(BuildTestsOnly)' != 'true'">
     <!-- Project name validation runs once in the outer build -->
     <ProjectToBuild Include="$(RepoRoot)eng\OuterPreBuild.proj" />
 
@@ -16,11 +19,13 @@
     <ProjectToBuild Include="$(RepoRoot)eng\dashboardpack\**\*.csproj" />
 
     <ProjectToBuild Include="$(RepoRoot)playground\**\*.csproj" />
+  </ItemGroup>
 
-    <!-- `$(SkipTestProjects)` allows skipping test projects from being
-          included in the build at all. This is useful for cases like when we are
-          just building the packages, and don't need to build the test projects. -->
-    <ProjectToBuild Include="$(RepoRoot)tests\**\*.csproj" Condition="'$(SkipTestProjects)' != 'true'" />
+  <!-- `$(SkipTestProjects)` allows skipping test projects from being
+        included in the build at all. This is useful for cases like when we are
+        just building the packages, and don't need to build the test projects. -->
+  <ItemGroup Condition="'$(SkipManagedBuild)' != 'true' and '$(SkipTestProjects)' != 'true'">
+    <ProjectToBuild Include="$(RepoRoot)tests\**\*.csproj" />
   </ItemGroup>
 
   <!-- Extension build project -->