Update azurerm_policy_set_definition - Fix #8663

azurerm/internal/services/policy/policy_set_definition_resource.go

@@ -444,8 +444,8 @@ func expandAzureRMPolicySetDefinitionPolicyDefinitions(input []interface{}) (*[]
 		v := item.(map[string]interface{})
 
 		parameters := make(map[string]*policy.ParameterValuesValue)
-		if p, ok := v["parameter_values"]; ok {
-			if err := json.Unmarshal([]byte(p.(string)), &parameters); err != nil {
+		if p, ok := v["parameter_values"].(string); ok && p != "" {
+			if err := json.Unmarshal([]byte(p), &parameters); err != nil {
 				return nil, fmt.Errorf("unmarshalling `parameter_values`: %+v", err)
 			}
 		}

azurerm/internal/services/policy/tests/policy_set_definition_resource_test.go

@@ -103,6 +103,24 @@ func TestAccAzureRMPolicySetDefinition_custom(t *testing.T) {
 	})
 }
 
+func TestAccAzureRMPolicySetDefinition_customNoParameter(t *testing.T) {
+	data := acceptance.BuildTestData(t, "azurerm_policy_set_definition", "test")
+	resource.ParallelTest(t, resource.TestCase{
+		PreCheck:     func() { acceptance.PreCheck(t) },
+		Providers:    acceptance.SupportedProviders,
+		CheckDestroy: testCheckAzureRMPolicySetDefinitionDestroy,
+		Steps: []resource.TestStep{
+			{
+				Config: testAzureRMPolicySetDefinition_customNoParameter(data),
+				Check: resource.ComposeTestCheckFunc(
+					testCheckAzureRMPolicySetDefinitionExists(data.ResourceName),
+				),
+			},
+			data.ImportStep(),
+		},
+	})
+}
+
 func TestAccAzureRMPolicySetDefinition_customWithPolicyReferenceID(t *testing.T) {
 	data := acceptance.BuildTestData(t, "azurerm_policy_set_definition", "test")
 
@@ -367,6 +385,23 @@ VALUES
 `, template, data.RandomInteger, data.RandomInteger)
 }
 
+func testAzureRMPolicySetDefinition_customNoParameter(data acceptance.TestData) string {
+	template := testAzureRMPolicySetDefinition_templateNoParameter(data)
+	return fmt.Sprintf(`
+%s
+
+resource "azurerm_policy_set_definition" "test" {
+  name         = "acctestPolSet-%d"
+  policy_type  = "Custom"
+  display_name = "acctestPolSet-display-%d"
+
+  policy_definition_reference {
+    policy_definition_id = azurerm_policy_definition.test.id
+  }
+}
+`, template, data.RandomInteger, data.RandomInteger)
+}
+
 func testAzureRMPolicySetDefinition_managementGroupDeprecated(data acceptance.TestData) string {
 	return fmt.Sprintf(`
 provider "azurerm" {
@@ -619,6 +654,35 @@ PARAMETERS
 `, data.RandomInteger, data.RandomInteger)
 }
 
+func testAzureRMPolicySetDefinition_templateNoParameter(data acceptance.TestData) string {
+	return fmt.Sprintf(`
+provider "azurerm" {
+  features {}
+}
+
+resource "azurerm_policy_definition" "test" {
+  name         = "acctestpol-%d"
+  policy_type  = "Custom"
+  mode         = "All"
+  display_name = "acctestpol-%d"
+
+  policy_rule = <<POLICY_RULE
+	{
+    "if": {
+      "not": {
+        "field": "location",
+        "equals": "%s"
+      }
+    },
+    "then": {
+      "effect": "deny"
+    }
+  }
+POLICY_RULE
+}
+`, data.RandomInteger, data.RandomInteger, data.Locations.Primary)
+}
+
 func testCheckAzureRMPolicySetDefinitionExists(resourceName string) resource.TestCheckFunc {
 	return func(s *terraform.State) error {
 		client := acceptance.AzureProvider.Meta().(*clients.Client).Policy.SetDefinitionsClient