added test to catch creationTimestamp bug regressions

internal/matchers/matchers_test.go

@@ -20,6 +20,7 @@ import (
 	"testing"
 
 	. "github.com/onsi/gomega"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 )
 
@@ -179,6 +180,34 @@ func TestEqualObjectMatcher(t *testing.T) {
 			want: false,
 		},
 
+		// This tests specific behaviour in how Kubernetes marshals the zero value of metav1.Time{}.
+		{
+			name: "Creation timestamp set to empty value on both original and modified",
+			original: &unstructured.Unstructured{
+				Object: map[string]interface{}{
+					"spec": map[string]interface{}{
+						"A": "A",
+					},
+					"metadata": map[string]interface{}{
+						"selfLink":          "foo",
+						"creationTimestamp": metav1.Time{},
+					},
+				},
+			},
+			modified: &unstructured.Unstructured{
+				Object: map[string]interface{}{
+					"spec": map[string]interface{}{
+						"A": "A",
+					},
+					"metadata": map[string]interface{}{
+						"selfLink":          "foo",
+						"creationTimestamp": metav1.Time{},
+					},
+				},
+			},
+			want: true,
+		},
+
 		// Cases to test diff when fields exist only in modified object.
 		{
 			name: "Field only in modified",
@@ -212,6 +241,28 @@ func TestEqualObjectMatcher(t *testing.T) {
 			},
 			want: false,
 		},
+		{
+			name: "Creation timestamp exists on modified but not on original",
+			original: &unstructured.Unstructured{
+				Object: map[string]interface{}{
+					"spec": map[string]interface{}{
+						"A": "A",
+					},
+				},
+			},
+			modified: &unstructured.Unstructured{
+				Object: map[string]interface{}{
+					"spec": map[string]interface{}{
+						"A": "A",
+					},
+					"metadata": map[string]interface{}{
+						"selfLink":          "foo",
+						"creationTimestamp": "2021-11-03T11:05:17Z",
+					},
+				},
+			},
+			want: false,
+		},
 
 		// Test when fields are exists only in the original object.
 		{
@@ -246,6 +297,29 @@ func TestEqualObjectMatcher(t *testing.T) {
 			},
 			want: false,
 		},
+		{
+			name: "Creation timestamp exists on original but not on modified",
+			original: &unstructured.Unstructured{
+				Object: map[string]interface{}{
+					"spec": map[string]interface{}{
+						"A": "A",
+					},
+					"metadata": map[string]interface{}{
+						"selfLink":          "foo",
+						"creationTimestamp": "2021-11-03T11:05:17Z",
+					},
+				},
+			},
+			modified: &unstructured.Unstructured{
+				Object: map[string]interface{}{
+					"spec": map[string]interface{}{
+						"A": "A",
+					},
+				},
+			},
+
+			want: false,
+		},
 
 		// Test metadata fields computed by the system or in status are compared.
 		{