Fixes null parameter overrides default #2795 (#2797)

docs/CHANGELOG-v1.md

@@ -32,6 +32,12 @@ See [upgrade notes][1] for helpful information when upgrading from previous vers
 
 ## Unreleased
 
+What's changed since v1.35.0:
+
+- Bug fixes:
+  - Fixed null parameter overrides default value by @BernieWhite.
+    [#2795](https://github.com/Azure/PSRule.Rules.Azure/issues/2795)
+
 ## v1.35.0
 
 What's changed since v1.34.2:

src/PSRule.Rules.Azure/Data/Template/TemplateVisitor.cs

@@ -352,6 +352,9 @@ private bool AssignParameterLiteral(string name, JObject parameter)
 
             private void AddParameterAssignment(string name, JToken value)
             {
+                if (value == null || value.Type == JTokenType.Null || value.Type == JTokenType.Undefined)
+                    return;
+
                 _ParameterAssignments.Add(name, value);
             }
 

tests/PSRule.Rules.Azure.Tests/TemplateVisitorTests.cs

@@ -1099,11 +1099,23 @@ public void UnionMockWithArray()
         /// Test case for https://github.com/Azure/PSRule.Rules.Azure/issues/2751.
         /// </summary>
         [Fact]
-        public void Index_into_mock_output_object()
+        public void ProcessTemplate_WhenIndexIntoMock_ShouldReturnMock()
         {
             var resources = ProcessTemplate(GetSourcePath("Tests.Bicep.35.json"), null, out _);
         }
 
+        /// <summary>
+        /// Test case for https://github.com/Azure/PSRule.Rules.Azure/issues/2795.
+        /// </summary>
+        [Fact]
+        public void ProcessTemplate_WhenParameterNullWithDefault_ShouldUseDefault()
+        {
+            var resources = ProcessTemplate(GetSourcePath("Tests.Bicep.27.json"), null, out _);
+
+            var actual = resources.FirstOrDefault(r => r["type"].Value<string>() == "Microsoft.Storage/storageAccounts");
+            Assert.Equal("Standard_LRS", actual["sku"]["name"].Value<string>());
+        }
+
         #region Helper methods
 
         private static string GetSourcePath(string fileName)

tests/PSRule.Rules.Azure.Tests/Tests.Bicep.27.bicep

@@ -3,6 +3,9 @@
 
 module child 'Tests.Bicep.27.child.bicep' = {
   name: 'child'
+  params: {
+    skuName: null
+  }
 }
 
 output childFromFor string = child.outputs.fromFor

tests/PSRule.Rules.Azure.Tests/Tests.Bicep.27.child.bicep

@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT License.
 
+param skuName string = 'Standard_LRS'
 param minTLSVersion string?
 param corsRules corsRule
 
@@ -17,11 +18,13 @@ param accessPolicies array?
 @secure()
 param secrets object?
 
-var formattedAccessPolicies = [for accessPolicy in (accessPolicies ?? []): {
-  objectId: accessPolicy.objectId
-  tenantId: contains(accessPolicy, 'tenantId') ? accessPolicy.tenantId : tenant().tenantId
-  permissions: {}
-}]
+var formattedAccessPolicies = [
+  for accessPolicy in (accessPolicies ?? []): {
+    objectId: accessPolicy.objectId
+    tenantId: contains(accessPolicy, 'tenantId') ? accessPolicy.tenantId : tenant().tenantId
+    permissions: {}
+  }
+]
 
 var secretList = secrets.?secureList ?? []
 
@@ -30,7 +33,7 @@ resource storage 'Microsoft.Storage/storageAccounts@2023-01-01' = {
   #disable-next-line no-loc-expr-outside-params
   location: resourceGroup().location
   sku: {
-    name: 'Standard_LRS'
+    name: skuName
   }
   kind: 'StorageV2'
   properties: {
@@ -61,12 +64,14 @@ resource kv 'Microsoft.KeyVault/vaults@2023-07-01' = {
   }
 }
 
-resource kvSecret 'Microsoft.KeyVault/vaults/secrets@2023-07-01' = [for item in secretList: {
-  name: item.name
-  properties: {
-    value: item.value
+resource kvSecret 'Microsoft.KeyVault/vaults/secrets@2023-07-01' = [
+  for item in secretList: {
+    name: item.name
+    properties: {
+      value: item.value
+    }
   }
-}]
+]
 
 resource storageAccount_objectReplicationPolicy 'Microsoft.Storage/storageAccounts/objectReplicationPolicies@2022-09-01' = {
   name: 'default'
@@ -85,22 +90,24 @@ resource storageAccount_objectReplicationPolicy 'Microsoft.Storage/storageAccoun
   }
 }
 
-resource storageAccount_objectReplicationPolicyItems 'Microsoft.Storage/storageAccounts/objectReplicationPolicies@2022-09-01' = [for (item, index) in [ 1 ]: {
-  name: 'default${index}'
-  parent: storage
-  properties: {
-    sourceAccount: 'sourceId'
-    destinationAccount: 'destId'
-    rules: [
-      {
-        ruleId: null
-        sourceContainer: 'source'
-        destinationContainer: 'dest'
-        filters: null
-      }
-    ]
+resource storageAccount_objectReplicationPolicyItems 'Microsoft.Storage/storageAccounts/objectReplicationPolicies@2022-09-01' = [
+  for (item, index) in [1]: {
+    name: 'default${index}'
+    parent: storage
+    properties: {
+      sourceAccount: 'sourceId'
+      destinationAccount: 'destId'
+      rules: [
+        {
+          ruleId: null
+          sourceContainer: 'source'
+          destinationContainer: 'dest'
+          filters: null
+        }
+      ]
+    }
   }
-}]
+]
 
 output policyId string = storageAccount_objectReplicationPolicy.properties.policyId
 output ruleIds string[] = map(storageAccount_objectReplicationPolicy.properties.rules, rule => rule.ruleId)

tests/PSRule.Rules.Azure.Tests/Tests.Bicep.27.json

@@ -4,8 +4,8 @@
   "metadata": {
     "_generator": {
       "name": "bicep",
-      "version": "0.23.1.45101",
-      "templateHash": "1063354008601109842"
+      "version": "0.26.54.24096",
+      "templateHash": "7737727980270162371"
     }
   },
   "resources": [
@@ -18,15 +18,20 @@
           "scope": "inner"
         },
         "mode": "Incremental",
+        "parameters": {
+          "skuName": {
+            "value": null
+          }
+        },
         "template": {
           "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
           "languageVersion": "2.0",
           "contentVersion": "1.0.0.0",
           "metadata": {
             "_generator": {
               "name": "bicep",
-              "version": "0.23.1.45101",
-              "templateHash": "11238883118622659404"
+              "version": "0.26.54.24096",
+              "templateHash": "14665743710501821887"
             }
           },
           "definitions": {
@@ -68,6 +73,10 @@
             }
           },
           "parameters": {
+            "skuName": {
+              "type": "string",
+              "defaultValue": "Standard_LRS"
+            },
             "minTLSVersion": {
               "type": "string",
               "nullable": true
@@ -118,7 +127,7 @@
               "name": "test",
               "location": "[resourceGroup().location]",
               "sku": {
-                "name": "Standard_LRS"
+                "name": "[parameters('skuName')]"
               },
               "kind": "StorageV2",
               "properties": {