pkg: test ResourceDeletionProtection valid webhook

In this commit, we add unit tests for the `ValidatingAdmission` validation webhook
specifically for the resource deletion protection feature. These tests ensure
that the webhook correctly handles various admission scenarios:

- Tests the behavior when decoding the request object fails, verifying that admission
is denied with an appropriate error message.
- Ensures that resources labeled with `DeletionProtectionAlways` are denied deletion,
validating that the error message is returned.
- Confirms that resources without the deletion protection label are allowed to be deleted
without errors.
- Validates that resources with other labels are not impacted and are allowed to be deleted.
- Confirms that non-delete operations (e.g., create) are allowed by default.

Signed-off-by: Mohamed Awnallah <[email protected]>

Author: mohamedawnallah

Diff for: pkg/webhook/resourcedeletionprotection/validating_test.go

@@ -0,0 +1,166 @@
+/*
+Copyright 2024 The Karmada Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package resourcedeletionprotection
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net/http"
+	"reflect"
+	"testing"
+
+	workv1alpha2 "github.com/karmada-io/karmada/pkg/apis/work/v1alpha2"
+	v1 "k8s.io/api/admission/v1"
+	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
+	"k8s.io/apimachinery/pkg/runtime"
+	"sigs.k8s.io/controller-runtime/pkg/webhook/admission"
+)
+
+type fakeValidationDecoder struct {
+	err error
+	obj runtime.Object
+}
+
+// Decode mocks the Decode method of admission.Decoder.
+func (f *fakeValidationDecoder) Decode(_ admission.Request, obj runtime.Object) error {
+	if f.err != nil {
+		return f.err
+	}
+	if f.obj != nil {
+		reflect.ValueOf(obj).Elem().Set(reflect.ValueOf(f.obj).Elem())
+	}
+	return nil
+}
+
+// DecodeRaw mocks the DecodeRaw method of admission.Decoder.
+func (f *fakeValidationDecoder) DecodeRaw(rawObj runtime.RawExtension, obj runtime.Object) error {
+	if f.err != nil {
+		return f.err
+	}
+	if rawObj.Object != nil {
+		reflect.ValueOf(obj).Elem().Set(reflect.ValueOf(rawObj.Object).Elem())
+	}
+	return nil
+}
+
+func TestValidatingAdmission_Handle(t *testing.T) {
+	tests := []struct {
+		name    string
+		decoder admission.Decoder
+		req     admission.Request
+		want    admission.Response
+	}{
+		{
+			name: "Handle_DecodeRawError_DeniesAdmission",
+			decoder: &fakeValidationDecoder{
+				err: errors.New("decode error"),
+			},
+			req: admission.Request{
+				AdmissionRequest: v1.AdmissionRequest{
+					Operation: v1.Delete,
+				},
+			},
+			want: admission.Errored(http.StatusBadRequest, errors.New("decode error")),
+		},
+		{
+			name:    "Handle_DeleteWithProtectionLabel_DeniesAdmission",
+			decoder: &fakeValidationDecoder{},
+			req: admission.Request{
+				AdmissionRequest: v1.AdmissionRequest{
+					Operation: v1.Delete,
+					OldObject: runtime.RawExtension{
+						Object: &unstructured.Unstructured{
+							Object: map[string]interface{}{
+								"metadata": map[string]interface{}{
+									"labels": map[string]interface{}{
+										workv1alpha2.DeletionProtectionLabelKey: workv1alpha2.DeletionProtectionAlways,
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+			want: admission.Denied(fmt.Sprintf("This resource is protected, please make sure to remove the label: %s", workv1alpha2.DeletionProtectionLabelKey)),
+		},
+		{
+			name:    "Handle_DeleteWithoutLabel_AllowsAdmission",
+			decoder: &fakeValidationDecoder{},
+			req: admission.Request{
+				AdmissionRequest: v1.AdmissionRequest{
+					Operation: v1.Delete,
+					OldObject: runtime.RawExtension{
+						Object: &unstructured.Unstructured{
+							Object: map[string]interface{}{
+								"metadata": map[string]interface{}{
+									"labels": map[string]interface{}{},
+								},
+							},
+						},
+					},
+				},
+			},
+			want: admission.Allowed(""),
+		},
+		{
+			name:    "Handle_DeleteWithDifferentLabel_AllowsAdmission",
+			decoder: &fakeValidationDecoder{},
+			req: admission.Request{
+				AdmissionRequest: v1.AdmissionRequest{
+					Operation: v1.Delete,
+					OldObject: runtime.RawExtension{
+						Object: &unstructured.Unstructured{
+							Object: map[string]interface{}{
+								"metadata": map[string]interface{}{
+									"labels": map[string]interface{}{
+										"some-other-label": "some-value",
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+			want: admission.Allowed(""),
+		},
+		{
+			name: "Handle_CreateOperation_AllowsAdmission",
+			decoder: &fakeValidationDecoder{
+				err: errors.New("decode error"),
+			},
+			req: admission.Request{
+				AdmissionRequest: v1.AdmissionRequest{
+					Operation: v1.Create,
+				},
+			},
+			want: admission.Allowed(""),
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			v := &ValidatingAdmission{
+				Decoder: tt.decoder,
+			}
+			got := v.Handle(context.Background(), tt.req)
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("Handle() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}