Modify New-AzVmss Vmss Flex defaulting logic to avoid null reference errors (#17610)

* dev and test

* test json

* changelog

Co-authored-by: Dingmeng Xue <[email protected]>

Author: Sandido

src/Compute/Compute.Test/ScenarioTests/VirtualMachineScaleSetTests.cs

@@ -263,5 +263,12 @@ public void TestVirtualMachineScaleSetRepairsAction()
             TestRunner.RunTestScript("Test-VirtualMachineScaleSetRepairsAction");
         }
 
+        [Fact]
+        [Trait(Category.AcceptanceType, Category.CheckIn)]
+        public void TestVirtualMachineScaleSetOrchestrationModeNullChecks()
+        {
+            TestRunner.RunTestScript("Test-VirtualMachineScaleSetOrchestrationModeNullChecks");
+        }
+
     }
 }

src/Compute/Compute.Test/ScenarioTests/VirtualMachineScaleSetTests.ps1

@@ -2874,6 +2874,37 @@ function Test-VirtualMachineScaleSetFlexibleOModeDefaulting
     }
 }
 
+<#
+.SYNOPSIS
+Test Virtual Machine Scale Set OrchestrationMode NetworkAPIVersion null checks work
+#>
+function Test-VirtualMachineScaleSetOrchestrationModeNullChecks
+{
+    # Setup
+    $rgname = Get-ComputeTestResourceName;
+
+    try
+    {
+        # Common
+        $loc = "eastus";
+
+        New-AzResourceGroup -Name $rgname -Location $loc -Force;
+        $VMSSName = "sap-flex";
+        $omode = "Flexible";
+
+        # Create Vmss 
+        $vmssConfig = New-AzVmssConfig -Location $loc -PlatformFaultDomainCount 3 -OrchestrationMode $omode;
+        $vmss = New-AzVmss -ResourceGroupName $rgname -Name $VMSSName -VirtualMachineScaleSet $vmssConfig;
+        Assert-AreEqual $omode $vmss.OrchestrationMode;
+
+    }
+    finally
+    {
+        # Cleanup
+        Clean-ResourceGroup $rgname;
+    }
+}
+
 <#
 .SYNOPSIS
 Test Add and remove Vmss Run Command.