test: add managed cluster webhook test cases

Signed-off-by: Carlos Salas <carlos.salas@suse.com>

exp/api/v1beta1/gcpmanagedcluster_webhook_test.go

@@ -0,0 +1,114 @@
+/*
+Copyright 2022 The Kubernetes 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 v1beta1
+
+import (
+	"testing"
+
+	. "github.com/onsi/gomega"
+	infrav1 "sigs.k8s.io/cluster-api-provider-gcp/api/v1beta1"
+)
+
+func TestGCPManagedClusterValidatingWebhookUpdate(t *testing.T) {
+	tests := []struct {
+		name        string
+		expectError bool
+		spec        GCPManagedClusterSpec
+	}{
+		{
+			name:        "request to change mutable field additional labels",
+			expectError: false,
+			spec: GCPManagedClusterSpec{
+				Project: "old-project",
+				Region:  "us-west1",
+				CredentialsRef: &infrav1.ObjectReference{
+					Namespace: "default",
+					Name:      "credsref",
+				},
+				AdditionalLabels: map[string]string{
+					"testKey": "testVal",
+				},
+			},
+		},
+		{
+			name:        "request to change immutable field project",
+			expectError: true,
+			spec: GCPManagedClusterSpec{
+				Project: "new-project",
+				Region:  "us-west1",
+				CredentialsRef: &infrav1.ObjectReference{
+					Namespace: "default",
+					Name:      "credsref",
+				},
+			},
+		},
+		{
+			name:        "request to change immutable field region",
+			expectError: true,
+			spec: GCPManagedClusterSpec{
+				Project: "old-project",
+				Region:  "us-central1",
+				CredentialsRef: &infrav1.ObjectReference{
+					Namespace: "default",
+					Name:      "credsref",
+				},
+			},
+		},
+		{
+			name:        "request to change immutable field credentials ref",
+			expectError: true,
+			spec: GCPManagedClusterSpec{
+				Project: "old-project",
+				Region:  "us-central1",
+				CredentialsRef: &infrav1.ObjectReference{
+					Namespace: "new-ns",
+					Name:      "new-name",
+				},
+			},
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			g := NewWithT(t)
+
+			newMC := &GCPManagedCluster{
+				Spec: tc.spec,
+			}
+			oldMC := &GCPManagedCluster{
+				Spec: GCPManagedClusterSpec{
+					Project: "old-project",
+					Region:  "us-west1",
+					CredentialsRef: &infrav1.ObjectReference{
+						Namespace: "default",
+						Name:      "credsref",
+					},
+				},
+			}
+
+			warn, err := newMC.ValidateUpdate(oldMC)
+
+			if tc.expectError {
+				g.Expect(err).To(HaveOccurred())
+			} else {
+				g.Expect(err).ToNot(HaveOccurred())
+			}
+			// Nothing emits warnings yet
+			g.Expect(warn).To(BeEmpty())
+		})
+	}
+}