pkg/webhook: test Multi-Cluster Ingress

In this commit we introduce unit tests for the `Validation Admission`. These
tests ensure correct behavior for various validation scenarios and improve coverage:

- Tests the behavior when decoding the request object fails, verifying
  that admission is denied with an appropriate error message.
- Validates that the webhook denies admission when encountering invalid values in the
  `MultiClusterIngress` spec, ensuring error messaging.
- Confirms that valid `MultiClusterIngress` objects are admitted without errors.

Signed-off-by: Mohamed Awnallah <mohamedmohey2352@gmail.com>

pkg/webhook/multiclusteringress/validating_test.go

@@ -0,0 +1,448 @@
+/*
+Copyright 2023 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 multiclusteringress
+
+import (
+	"context"
+	"errors"
+	"net/http"
+	"reflect"
+	"strings"
+	"testing"
+
+	admissionv1 "k8s.io/api/admission/v1"
+	networkingv1 "k8s.io/api/networking/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime"
+	"sigs.k8s.io/controller-runtime/pkg/webhook/admission"
+
+	networkingv1alpha1 "github.com/karmada-io/karmada/pkg/apis/networking/v1alpha1"
+)
+
+// ResponseType represents the type of admission response.
+type ResponseType string
+
+const (
+	Denied  ResponseType = "Denied"
+	Allowed ResponseType = "Allowed"
+	Errored ResponseType = "Errored"
+)
+
+// TestResponse is used to define expected response in a test case.
+type TestResponse struct {
+	Type    ResponseType
+	Message string
+}
+
+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(rawObject runtime.RawExtension, obj runtime.Object) error {
+	if f.err != nil {
+		return f.err
+	}
+	if rawObject.Object != nil {
+		reflect.ValueOf(obj).Elem().Set(reflect.ValueOf(rawObject.Object).Elem())
+		return nil
+	}
+	return errors.New("decode raw object error; object is nil")
+}
+
+func TestValidatingAdmission_Handle(t *testing.T) {
+	tests := []struct {
+		name    string
+		decoder admission.Decoder
+		req     admission.Request
+		want    TestResponse
+	}{
+		{
+			name: "Handle_DecodeError_DeniesAdmission",
+			decoder: &fakeValidationDecoder{
+				err: errors.New("decode error"),
+			},
+			req: admission.Request{},
+			want: TestResponse{
+				Type:    Errored,
+				Message: "decode error",
+			},
+		},
+		{
+			name:    "Handle_DecodeOldObjectError_DeniesAdmission",
+			decoder: &fakeValidationDecoder{},
+			req: admission.Request{
+				AdmissionRequest: admissionv1.AdmissionRequest{
+					Operation: admissionv1.Update,
+					OldObject: runtime.RawExtension{
+						Object: nil,
+					},
+				},
+			},
+			want: TestResponse{
+				Type:    Errored,
+				Message: "decode raw object error; object is nil",
+			},
+		},
+		{
+			name: "Handle_UpdateMCIWithInvalidSpec_DeniesAdmission",
+			decoder: &fakeValidationDecoder{
+				obj: &networkingv1alpha1.MultiClusterIngress{
+					ObjectMeta: metav1.ObjectMeta{
+						Name:            "test-mci",
+						Namespace:       "test-namespace",
+						ResourceVersion: "1001",
+					},
+					Spec: networkingv1.IngressSpec{
+						DefaultBackend: &networkingv1.IngressBackend{
+							Service: &networkingv1.IngressServiceBackend{
+								Name: "test-new-backend",
+								Port: networkingv1.ServiceBackendPort{
+									Name:   "",
+									Number: 80,
+								},
+							},
+						},
+						Rules: []networkingv1.IngressRule{
+							{Host: "10.0.0.5"},
+						},
+					},
+				},
+			},
+			req: admission.Request{
+				AdmissionRequest: admissionv1.AdmissionRequest{
+					Operation: admissionv1.Update,
+					OldObject: runtime.RawExtension{
+						Object: &networkingv1alpha1.MultiClusterIngress{
+							ObjectMeta: metav1.ObjectMeta{
+								Name:            "test-mci",
+								Namespace:       "test-namespace",
+								ResourceVersion: "1000",
+							},
+							Spec: networkingv1.IngressSpec{
+								DefaultBackend: &networkingv1.IngressBackend{
+									Service: &networkingv1.IngressServiceBackend{
+										Name: "test-backend",
+										Port: networkingv1.ServiceBackendPort{
+											Name:   "",
+											Number: 80,
+										},
+									},
+								},
+								Rules: []networkingv1.IngressRule{
+									{Host: "127.0.0.1"},
+								},
+							},
+						},
+					},
+				},
+			},
+			want: TestResponse{
+				Type:    Denied,
+				Message: "Invalid value: \"10.0.0.5\": must be a DNS name, not an IP address",
+			},
+		},
+		{
+			name: "Handle_CreateMCIWithInvalidSpec_DeniesAdmission",
+			decoder: &fakeValidationDecoder{
+				obj: &networkingv1alpha1.MultiClusterIngress{
+					ObjectMeta: metav1.ObjectMeta{
+						Name:            "test-mci",
+						Namespace:       "test-namespace",
+						ResourceVersion: "1000",
+					},
+					Spec: networkingv1.IngressSpec{
+						DefaultBackend: nil,
+						Rules:          nil,
+					},
+				},
+			},
+			req: admission.Request{
+				AdmissionRequest: admissionv1.AdmissionRequest{
+					Operation: admissionv1.Create,
+				},
+			},
+			want: TestResponse{
+				Type:    Denied,
+				Message: "either `defaultBackend` or `rules` must be specified",
+			},
+		},
+		{
+			name: "Handle_ValidationSucceeds_AllowsAdmission",
+			decoder: &fakeValidationDecoder{
+				obj: &networkingv1alpha1.MultiClusterIngress{
+					ObjectMeta: metav1.ObjectMeta{
+						Name:            "test-mci",
+						Namespace:       "test-namespace",
+						ResourceVersion: "1001",
+					},
+					Spec: networkingv1.IngressSpec{
+						DefaultBackend: &networkingv1.IngressBackend{
+							Service: &networkingv1.IngressServiceBackend{
+								Name: "test-new-backend",
+								Port: networkingv1.ServiceBackendPort{
+									Name:   "",
+									Number: 80,
+								},
+							},
+						},
+						Rules: []networkingv1.IngressRule{
+							{Host: "test-new-backend.com"},
+						},
+					},
+				},
+			},
+			req: admission.Request{
+				AdmissionRequest: admissionv1.AdmissionRequest{
+					Operation: admissionv1.Update,
+					OldObject: runtime.RawExtension{
+						Object: &networkingv1alpha1.MultiClusterIngress{
+							ObjectMeta: metav1.ObjectMeta{
+								Name:            "test-mci",
+								Namespace:       "test-namespace",
+								ResourceVersion: "1000",
+							},
+							Spec: networkingv1.IngressSpec{
+								DefaultBackend: &networkingv1.IngressBackend{
+									Service: &networkingv1.IngressServiceBackend{
+										Name: "test-backend",
+										Port: networkingv1.ServiceBackendPort{
+											Name:   "",
+											Number: 80,
+										},
+									},
+								},
+								Rules: []networkingv1.IngressRule{
+									{Host: "test-backend.com"},
+								},
+							},
+						},
+					},
+				},
+			},
+			want: TestResponse{
+				Type:    Allowed,
+				Message: "",
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			v := &ValidatingAdmission{
+				Decoder: tt.decoder,
+			}
+			got := v.Handle(context.Background(), tt.req)
+
+			// Extract type and message from the actual response.
+			gotType := extractResponseType(got)
+			gotMessage := extractErrorMessage(got)
+
+			if gotType != tt.want.Type || !strings.Contains(gotMessage, tt.want.Message) {
+				t.Errorf("Handle() = {Type: %v, Message: %v}, want {Type: %v, Message: %v}", gotType, gotMessage, tt.want.Type, tt.want.Message)
+			}
+		})
+	}
+}
+
+func TestValidatingSpec_validateMCIUpdate(t *testing.T) {
+	tests := []struct {
+		name    string
+		oldMcs  *networkingv1alpha1.MultiClusterIngress
+		newMcs  *networkingv1alpha1.MultiClusterIngress
+		wantErr bool
+		errMsg  string
+	}{
+		{
+			name: "validateMCIUpdate_ValidMetadataUpdate_NoError",
+			oldMcs: &networkingv1alpha1.MultiClusterIngress{
+				ObjectMeta: metav1.ObjectMeta{
+					Name:            "test-mci",
+					Namespace:       "test-namespace",
+					Labels:          map[string]string{"key": "oldValue"},
+					ResourceVersion: "1000",
+				},
+				Spec: networkingv1.IngressSpec{
+					DefaultBackend: &networkingv1.IngressBackend{
+						Service: &networkingv1.IngressServiceBackend{
+							Name: "test-backend",
+							Port: networkingv1.ServiceBackendPort{
+								Name:   "",
+								Number: 80,
+							},
+						},
+					},
+					Rules: []networkingv1.IngressRule{
+						{Host: "test-backend.com"},
+					},
+				},
+			},
+			newMcs: &networkingv1alpha1.MultiClusterIngress{
+				ObjectMeta: metav1.ObjectMeta{
+					Name:            "test-mci",
+					Namespace:       "test-namespace",
+					Labels:          map[string]string{"key": "oldValue"},
+					ResourceVersion: "1001",
+				},
+				Spec: networkingv1.IngressSpec{
+					DefaultBackend: &networkingv1.IngressBackend{
+						Service: &networkingv1.IngressServiceBackend{
+							Name: "test-new-backend",
+							Port: networkingv1.ServiceBackendPort{
+								Name:   "",
+								Number: 80,
+							},
+						},
+					},
+					Rules: []networkingv1.IngressRule{
+						{Host: "test-new-backend.com"},
+					},
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name: "validateMCIUpdate_InvalidMetadataUpdate_Error",
+			oldMcs: &networkingv1alpha1.MultiClusterIngress{
+				ObjectMeta: metav1.ObjectMeta{
+					Name:            "test-mci",
+					Namespace:       "test-namespace",
+					ResourceVersion: "1000",
+				},
+			},
+			newMcs: &networkingv1alpha1.MultiClusterIngress{
+				ObjectMeta: metav1.ObjectMeta{
+					Name:            "mutated-name",
+					Namespace:       "test-namespace",
+					ResourceVersion: "1001",
+				},
+			},
+			wantErr: true,
+			errMsg:  "metadata.name: Invalid value: \"mutated-name\"",
+		},
+		{
+			name: "validateMCSUpdate_InvalidIngressLoadBalancerStatus_Error",
+			oldMcs: &networkingv1alpha1.MultiClusterIngress{
+				ObjectMeta: metav1.ObjectMeta{
+					Name:            "test-mci",
+					Namespace:       "test-namespace",
+					ResourceVersion: "1000",
+				},
+				Spec: networkingv1.IngressSpec{
+					DefaultBackend: &networkingv1.IngressBackend{
+						Service: &networkingv1.IngressServiceBackend{
+							Name: "test-backend",
+							Port: networkingv1.ServiceBackendPort{
+								Name:   "",
+								Number: 80,
+							},
+						},
+					},
+					Rules: []networkingv1.IngressRule{
+						{Host: "test-backend.com"},
+					},
+				},
+				Status: networkingv1alpha1.MultiClusterIngressStatus{
+					IngressStatus: networkingv1.IngressStatus{
+						LoadBalancer: networkingv1.IngressLoadBalancerStatus{
+							Ingress: []networkingv1.IngressLoadBalancerIngress{
+								{IP: "127.0.0.1", Hostname: "test-backend.com"},
+							},
+						},
+					},
+				},
+			},
+			newMcs: &networkingv1alpha1.MultiClusterIngress{
+				ObjectMeta: metav1.ObjectMeta{
+					Name:            "test-mci",
+					Namespace:       "test-namespace",
+					ResourceVersion: "1001",
+				},
+				Spec: networkingv1.IngressSpec{
+					DefaultBackend: &networkingv1.IngressBackend{
+						Service: &networkingv1.IngressServiceBackend{
+							Name: "test-new-backend",
+							Port: networkingv1.ServiceBackendPort{
+								Name:   "",
+								Number: 80,
+							},
+						},
+					},
+					Rules: []networkingv1.IngressRule{
+						{Host: "test-new-backend.com"},
+					},
+				},
+				Status: networkingv1alpha1.MultiClusterIngressStatus{
+					IngressStatus: networkingv1.IngressStatus{
+						LoadBalancer: networkingv1.IngressLoadBalancerStatus{
+							Ingress: []networkingv1.IngressLoadBalancerIngress{
+								{IP: "test-new-backend.com", Hostname: "test-new-backend.com"},
+							},
+						},
+					},
+				},
+			},
+			wantErr: true,
+			errMsg:  "Invalid value: \"test-new-backend.com\": must be a valid IP address",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			errs := validateMCIUpdate(tt.oldMcs, tt.newMcs)
+			if (len(errs) > 0) != tt.wantErr {
+				t.Errorf("validateMCSUpdate() gotErr = %v, wantErr %v", len(errs) > 0, tt.wantErr)
+			}
+			if tt.wantErr && !strings.Contains(errs.ToAggregate().Error(), tt.errMsg) {
+				t.Errorf("Expected error message: %v, got: %v", tt.errMsg, errs.ToAggregate().Error())
+			}
+		})
+	}
+}
+
+// extractResponseType extracts the type of admission response.
+func extractResponseType(resp admission.Response) ResponseType {
+	if resp.Allowed {
+		return Allowed
+	}
+	if resp.Result != nil {
+		if resp.Result.Code == http.StatusBadRequest {
+			return Errored
+		}
+	}
+	return Denied
+}
+
+// extractErrorMessage extracts the error message from a Denied/Errored response.
+func extractErrorMessage(resp admission.Response) string {
+	if !resp.Allowed && resp.Result != nil {
+		return resp.Result.Message
+	}
+	return ""
+}