Add custom pester test

avm/ptn/mgmt-groups/subscription-placement/pester/main.tests.ps1

@@ -0,0 +1,31 @@
+param (
+    [Parameter(Mandatory = $false)]
+    [hashtable] $TestInputData = @{}
+)
+
+Describe 'Bicep Landing Zone (Sub) Vending Tests' {
+
+    BeforeAll {
+        $subscriptionId = $TestInputData.DeploymentOutputs.createdSubId.Value
+        Update-AzConfig -DisplayBreakingChangeWarning $false
+        Select-AzSubscription -subscriptionId $subscriptionId
+    }
+
+    Context 'Subscription Placement Tests' {
+        BeforeAll {
+            $subscriptionPlacementSummary = $TestInputData.DeploymentOutputs.subscriptionPlacementSummary.Value
+        }
+
+        It 'Should have a Subscription Placement Summary' {
+            $subscriptionPlacementSummary | Should -Not -BeNullOrEmpty
+        }
+
+        It 'Should contain the correct management group ID' {
+            $subscriptionPlacementSummary | Should -Contain 'test-mgmt-group'
+        }
+
+        It 'Should contain the correct subscription ID' {
+            $subscriptionPlacementSummary | Should -Contain $subscriptionId
+        }
+    }
+}