Edit New-AzSnapshot so it checks for already existing duplicate resource before creation

src/Compute/Compute.Test/ScenarioTests/DiskRPTests.cs

@@ -107,5 +107,12 @@ public void TestGetDiskEncryptionSetAssociatedResource()
         {
             TestRunner.RunTestScript("Test-GetDiskEncryptionSetAssociatedResource");
         }
+
+        [Fact]
+        [Trait(Category.AcceptanceType, Category.CheckIn)]
+        public void TestSnapshotDuplicateCreationFails()
+        {
+            TestRunner.RunTestScript("Test-SnapshotDuplicateCreationFails");
+        }
     }
 }

src/Compute/Compute.Test/ScenarioTests/DiskRPTests.ps1

@@ -246,7 +246,7 @@ function Test-Snapshot
         $snapshotconfig.EncryptionSettingsCollection.Enabled = $false;
         $snapshotconfig.EncryptionSettingsCollection.EncryptionSettings = $null;
         $snapshotconfig.CreationData.ImageReference = $null;
-        $job = New-AzSnapshot -ResourceGroupName $rgname -SnapshotName $snapshotname -Snapshot $snapshotconfig -AsJob;
+        $job = Update-AzSnapshot -ResourceGroupName $rgname -SnapshotName $snapshotname -Snapshot $snapshotconfig -AsJob;
         $result = $job | Wait-Job;
         Assert-AreEqual "Completed" $result.State;
 
@@ -619,7 +619,7 @@ function Test-SnapshotEncrypt
         Assert-AreEqual 0 $snapshotconfig.CreationData.ImageReference.Lun;
 
         $snapshotconfig.CreationData.ImageReference = $null;
-        $job = New-AzSnapshot -ResourceGroupName $rgname -SnapshotName $snapshotname -Snapshot $snapshotconfig -AsJob;
+        $job = Update-AzSnapshot -ResourceGroupName $rgname -SnapshotName $snapshotname -Snapshot $snapshotconfig -AsJob;
         $result = $job | Wait-Job;
         Assert-AreEqual "Completed" $result.State;
 
@@ -1336,4 +1336,42 @@ function Test-DiskConfigTierSectorSizeReadOnly
             # Cleanup
             Clean-ResourceGroup $rgname
 		}
+}
+
+<#
+.SYNOPSIS
+Test the New-AzSnapshot cmdlet throws an error when attempting to create a snapshot with 
+the same name in the same resource group. 
+#>
+function Test-SnapshotDuplicateCreationFails
+{
+    # Setup 
+    $rgname = Get-ComputeTestResourceName;
+    $loc = Get-ComputeVMLocation;
+
+    try
+    {
+        # Common
+        New-AzResourceGroup -Name $rgname -Location $loc -Force;
+        $snapshotName = "test1";
+
+        $snapshotconfig = New-AzSnapshotConfig -Location $loc -DiskSizeGB 5 -AccountType Standard_LRS -OsType Windows -CreateOption Empty;
+
+        $snapshot = New-AzSnapshot -ResourceGroupName $rgname -SnapshotName $snapshotName -Snapshot $snapshotconfig;
+        Assert-NotNull $snapshot;
+
+        # Assert duplicate snapshot fails to create.
+        Assert-ThrowsContains { $snapshot2 = New-AzSnapshot -ResourceGroupName $rgname -SnapshotName $snapshotName -Snapshot $snapshotconfig; } "Please use Update-AzSnapshot to update an existing Snapshot.";
+
+        # Assert update snapshot succeeds. 
+        $snapshotconfig2 = New-AzSnapshotUpdateConfig -DiskSizeGB 10 -AccountType Standard_LRS -OsType Windows;
+        $job = Update-AzSnapshot -ResourceGroupName $rgname -SnapshotName $snapshotName -SnapshotUpdate $snapshotconfig2 -AsJob;
+        $result = $job | Wait-Job;
+        Assert-AreEqual "Completed" $result.State;
+    }
+    finally
+    {
+        # Cleanup
+        Clean-ResourceGroup $rgname
+    }
 }

src/Compute/Compute.Test/ScenarioTests/GalleryTests.ps1

@@ -673,16 +673,15 @@ function Test-GalleryImageVersionDiskImage
 
         $snapshotname1 = 'ossnapshot' + $rgname;
         $snapshotconfig = New-AzSnapshotConfig -Location $loc -DiskSizeGB 5 -AccountType Standard_LRS -OsType Windows -CreateOption Empty -HyperVGeneration "V1";
-        $snapshot1 = New-AzSnapshot -ResourceGroupName $rgname -SnapshotName $snapshotname1 -Snapshot $snapshotconfig
+        $snapshot1 = Update-AzSnapshot -ResourceGroupName $rgname -SnapshotName $snapshotname1 -Snapshot $snapshotconfig
 
         $snapshotname2 = 'data1snapshot' + $rgname;
         $snapshotconfig = New-AzSnapshotConfig -Location $loc -DiskSizeGB 5 -AccountType Standard_LRS -OsType Windows -CreateOption Empty -HyperVGeneration "V1";
-        $snapshot2 = New-AzSnapshot -ResourceGroupName $rgname -SnapshotName $snapshotname2 -Snapshot $snapshotconfig
+        $snapshot2 = Update-AzSnapshot -ResourceGroupName $rgname -SnapshotName $snapshotname2 -Snapshot $snapshotconfig
 
         $snapshotname3 = 'data2snapshot' + $rgname;
         $snapshotconfig = New-AzSnapshotConfig -Location $loc -DiskSizeGB 5 -AccountType Standard_LRS -OsType Windows -CreateOption Empty -HyperVGeneration "V1";
-        $snapshot3 = New-AzSnapshot -ResourceGroupName $rgname -SnapshotName $snapshotname3 -Snapshot $snapshotconfig
-
+        $snapshot3 = Update-AzSnapshot -ResourceGroupName $rgname -SnapshotName $snapshotname3 -Snapshot $snapshotconfig
 
         $targetRegions = @(@{Name='South Central US';ReplicaCount=1;StorageAccountType='Standard_LRS'},@{Name='East US';ReplicaCount=2},@{Name='Central US'});        
         $tag = @{test1 = "testval1"; test2 = "testval2" };

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

@@ -3612,7 +3612,7 @@ function Test-VirtualMachineManagedDisk
         # Create OS snapshot from the VM
         $snapshotConfig = New-AzSnapshotConfig -SourceUri $vm.Storageprofile.OsDisk.ManagedDisk.Id -Location $loc -CreateOption Copy;
         $snapshotname = "ossnapshot";
-        New-AzSnapshot -Snapshot $snapshotConfig -SnapshotName $snapshotname -ResourceGroupName $rgname;
+        Update-AzSnapshot -Snapshot $snapshotConfig -SnapshotName $snapshotname -ResourceGroupName $rgname;
         $snapshot = Get-AzSnapshot -SnapshotName $snapshotname -ResourceGroupName $rgname;
 
         Assert-NotNull $snapshot.Id;

src/Compute/Compute/ChangeLog.md

@@ -22,6 +22,8 @@
 ## Upcoming Release
 * Edited Get-AzVm to filter by `-Name` prior to checking for throttling due to too many resources. 
 * New cmdlet `Start-AzVmssRollingExtensionUpgrade`.
+* Edited `New-AzSnapshot` cmdlet to check for existing snapshot with the same name in the same resource group. 
+    - Throws an error if a duplicate snapshot exists. 
 
 ## Version 4.6.0
 * Added `-VmssId` parameter to `New-AzVm`

src/Compute/Compute/Generated/Snapshot/SnapshotCreateOrUpdateMethod.cs

@@ -41,6 +41,21 @@ public override void ExecuteCmdlet()
             base.ExecuteCmdlet();
             ExecuteClientAction(() =>
             {
+                Snapshot existingResource;
+                try
+                { 
+                    existingResource = SnapshotsClient.Get(this.ResourceGroupName, this.SnapshotName);
+                }
+                catch
+                {
+                    existingResource = null;
+                }
+
+                if (existingResource != null)
+                {
+                    throw new Exception(string.Format("A Snapshot with name '{0}' in resource group '{1}' already exists. Please use Update-AzSnapshot to update an existing Snapshot.", this.SnapshotName, this.ResourceGroupName));
+                }
+
                 if (ShouldProcess(this.SnapshotName, VerbsCommon.New))
                 {
                     string resourceGroupName = this.ResourceGroupName;