add PR build to mock official build

azure-pipelines.yml

@@ -239,6 +239,16 @@ stages:
             continueOnError: true
             condition: failed()
 
+        # Mock official build
+        - job: MockOfficial
+          pool:
+            vmImage: windows-2019
+          steps:
+          - checkout: self
+            clean: true
+          - pwsh: .\eng\MockBuild.ps1
+            displayName: Build with OfficialBuildId
+
         # Linux
         - job: Linux
           pool:
@@ -311,7 +321,7 @@ stages:
           - checkout: self
             clean: true
           - script: .\Build.cmd -c Release
-          - script: .\tests\EndToEndBuildTests\EndToEndBuildTests -c Release
+          - script: .\tests\EndToEndBuildTests\EndToEndBuildTests.cmd -c Release
             displayName: End to end build tests
 
         # Source Build Windows

eng/MockBuild.ps1

@@ -0,0 +1,17 @@
+Set-StrictMode -version 2.0
+$ErrorActionPreference = "Stop"
+$BuildCategory = ""
+$BuildMessage = ""
+
+try {
+    $fakeBuildId = (Get-Date -Format "yyyyMMdd") + ".0"
+    $visualStudioDropName = "Products/mock/dotnet-fsharp/branch/$fakeBuildId"
+    .\Build.ps1 -build -restore -ci -bootstrap -binaryLog -pack -configuration Release /p:OfficialBuildId=$fakeBuildId /p:VisualStudioDropName=$visualStudioDropName
+}
+catch {
+    Write-Host $_
+    Write-Host $_.Exception
+    Write-Host $_.ScriptStackTrace
+    Write-PipelineTelemetryError -Category $script:BuildCategory -Message $script:BuildMessage
+    ExitWithExitCode 1
+}