update test

Author: huangpf

src/ResourceManager/Compute/Commands.Compute.Test/ScenarioTests/VirtualMachineTests.ps1

@@ -633,6 +633,8 @@ function Test-VirtualMachinePIRv2
         $p.StorageProfile.SourceImage = $null;
         $imgRef = Get-DefaultCRPImage;
         $p = Set-AzureVMSourceImage -VM $p -ImageReference $imgRef;
+        Assert-True { $p.ImageReference -ne $null };
+        Assert-True { $p.SourceImageId -eq $null };
 
         # TODO: Remove Data Disks for now
         $p.StorageProfile.DataDisks = $null;

src/ResourceManager/Compute/Commands.Compute/Models/PSVirtualMachine.cs

@@ -76,7 +76,7 @@ public ImageReference ImageReference
         {
             get
             {
-                if (this.StorageProfile != null && this.StorageProfile.SourceImage != null)
+                if (this.StorageProfile != null)
                 {
                     return this.StorageProfile.ImageReference;
                 }
@@ -89,7 +89,7 @@ public OSDisk OSDisk
         {
             get
             {
-                if (this.StorageProfile != null && this.StorageProfile.OSDisk != null)
+                if (this.StorageProfile != null)
                 {
                     return this.StorageProfile.OSDisk;
                 }