Fix constantly updating objects with a null struct

It was tricky to find an example of this. Most optional structs I found
would get populated with some default values, meaning they wouldn't be
omitted by the kube api.

Signed-off-by: Justin Kulikauskas <jkulikau@redhat.com>

controllers/configurationpolicy_utils.go

@@ -124,15 +124,21 @@ func equalObjWithSort(mergedObj interface{}, oldObj interface{}) (areEqual bool)
 		}
 
 		return false
-	default:
-		// NOTE: when type is string, int, bool
-		var oVal interface{}
-
+	default: // when mergedObj's type is string, int, bool, or nil
 		if oldObj == nil && mergedObj != nil {
+			// compare the zero value of mergedObj's type to mergedObj
 			ref := reflect.ValueOf(mergedObj)
-			oVal = reflect.Zero(ref.Type()).Interface()
+			zero := reflect.Zero(ref.Type()).Interface()
+
+			return fmt.Sprint(zero) == fmt.Sprint(mergedObj)
+		}
+
+		if mergedObj == nil && oldObj != nil {
+			// compare the zero value of oldObj's type to oldObj
+			ref := reflect.ValueOf(oldObj)
+			zero := reflect.Zero(ref.Type()).Interface()
 
-			return fmt.Sprint(oVal) == fmt.Sprint(mergedObj)
+			return fmt.Sprint(zero) == fmt.Sprint(oldObj)
 		}
 
 		if !reflect.DeepEqual(fmt.Sprint(mergedObj), fmt.Sprint(oldObj)) {

test/e2e/case31_policy_history_test.go

@@ -125,6 +125,33 @@ var _ = Describe("Test policy history messages when KubeAPI omits values in the
 			ExpectWithOffset(1, configlPlc).To(BeNil())
 		})
 	})
+
+	Describe("status should not toggle when a struct might be omitted", Ordered, func() {
+		const (
+			policyYAML       = rsrcPath + "event-policy-emptystruct.yaml"
+			policyName       = "test-policy-security-emptystruct"
+			configPolicyYAML = rsrcPath + "event-config-policy-emptystruct.yaml"
+			configPolicyName = "config-policy-event-emptystruct"
+		)
+
+		It("sets up a configuration policy with struct set to null", func() {
+			createConfigPolicyWithParent(policyYAML, policyName, configPolicyYAML)
+		})
+
+		It("checks the policy's history", func() {
+			doHistoryTest(policyYAML, policyName, configPolicyYAML, configPolicyName)
+		})
+
+		AfterAll(func() {
+			utils.Kubectl("delete", "policy", policyName, "-n", "managed", "--ignore-not-found")
+			configlPlc := utils.GetWithTimeout(clientManagedDynamic, gvrConfigPolicy,
+				configPolicyName, "managed", false, defaultTimeoutSeconds,
+			)
+			utils.Kubectl("delete", "event", "--field-selector=involvedObject.name="+policyName, "-n", "managed")
+			utils.Kubectl("delete", "event", "--field-selector=involvedObject.name="+configPolicyName, "-n", "managed")
+			ExpectWithOffset(1, configlPlc).To(BeNil())
+		})
+	})
 })
 
 func createConfigPolicyWithParent(parentPolicyYAML, parentPolicyName, configPolicyYAML string) {

test/resources/case31_policy_history/event-config-policy-emptystruct.yaml

@@ -0,0 +1,39 @@
+apiVersion: policy.open-cluster-management.io/v1
+kind: ConfigurationPolicy
+metadata:
+  name: config-policy-event-emptystruct
+  labels:
+    policy.open-cluster-management.io/policy: test-policy-security
+  ownerReferences:
+  - apiVersion: policy.open-cluster-management.io/v1
+    blockOwnerDeletion: false
+    controller: true
+    kind: Policy
+    name: test-policy-security-emptystruct
+    uid: 08bae967-4262-498a-84e9-d1f0e321b41e
+spec:
+  pruneObjectBehavior: DeleteAll  
+  remediationAction: enforce
+  namespaceSelector:
+    exclude:
+      - kube-public
+    include:
+      - default
+      - kube-system
+  object-templates:
+    - complianceType: musthave
+      objectDefinition:
+        action: DidTheThing
+        apiVersion: events.k8s.io/v1
+        eventTime: 2023-04-27T14:37:36.721589Z
+        kind: Event
+        metadata:
+          name: configpol-test-event
+          namespace: kube-system
+        note: Successfully did something
+        reason: Success
+        regarding: null
+        related: null
+        reportingController: ConfigPolicyTester
+        reportingInstance: configpol-history-test
+        type: Normal

test/resources/case31_policy_history/event-policy-emptystruct.yaml

@@ -0,0 +1,42 @@
+apiVersion: policy.open-cluster-management.io/v1
+kind: Policy
+metadata:
+  name: test-policy-security-emptystruct
+  annotations:
+    policy.open-cluster.management.io/standards: NIST-CSF
+    policy.open-cluster.management.io/categories: PR.PT Protective Technology
+    policy.open-cluster.management.io/controls: PR.PT-3 Least Functionality
+spec:
+  remediationAction: enforce
+  disabled: false
+  policy-templates:
+    - objectDefinition:
+        apiVersion: policy.open-cluster-management.io/v1
+        kind: ConfigurationPolicy
+        metadata:
+          name: config-policy-event-emptystruct
+        spec:
+          remediationAction: enforce
+          namespaceSelector:
+            exclude:
+              - kube-public
+            include:
+              - default
+              - kube-system
+          object-templates:
+            - complianceType: musthave
+              objectDefinition:
+                action: DidTheThing
+                apiVersion: events.k8s.io/v1
+                eventTime: 2023-04-27T14:37:36.721589Z
+                kind: Event
+                metadata:
+                  name: configpol-test-event
+                  namespace: kube-system
+                note: Successfully did something
+                reason: Success
+                regarding: null
+                related: null
+                reportingController: ConfigPolicyTester
+                reportingInstance: configpol-history-test
+                type: Normal