test(webhook/mutating): migrate tests to Ginkgo/Gomega (#5755)

* test(webhook/mutating): migrate tests to Ginkgo/Gomega

Signed-off-by: Harsh <harshmastic@gmail.com>

* fix(webhook/mutating): use GinkgoT().Setenv for env-var restoration

Address Copilot and Gemini review findings: replace manual
DeferCleanup(os.Unsetenv) with GinkgoT().Setenv() which automatically
saves and restores the prior environment variable value after the spec.

Signed-off-by: Harsh <harshmastic@gmail.com>

* test(webhook/mutating): add webhook_test.go for HandlerMap coverage

Signed-off-by: Harsh <harshmastic@gmail.com>

* fix(webhook/mutating): remove brittle HaveLen assertion from HandlerMap test

Signed-off-by: Harsh <harshmastic@gmail.com>

* fix(webhook/mutating): assert handler is non-nil before type check

Signed-off-by: Harsh <harshmastic@gmail.com>

---------

Signed-off-by: Harsh <harshmastic@gmail.com>

Author: hxrshxz

pkg/webhook/handler/mutating/mutating_handler_test.go

@@ -23,7 +23,6 @@ import (
 	"github.com/agiledragon/gomonkey/v2"
 	datav1alpha1 "github.com/fluid-cloudnative/fluid/api/v1alpha1"
 	"github.com/fluid-cloudnative/fluid/pkg/common"
-	"github.com/fluid-cloudnative/fluid/pkg/utils"
 	"github.com/fluid-cloudnative/fluid/pkg/utils/fake"
 	"github.com/fluid-cloudnative/fluid/pkg/webhook/plugins"
 	. "github.com/onsi/ginkgo/v2"
@@ -1465,7 +1464,6 @@ var _ = Describe("Handle - Global Injection Disabled", func() {
 	var (
 		decoder *admission.Decoder
 		s       *runtime.Scheme
-		patch   *gomonkey.Patches
 	)
 
 	BeforeEach(func() {
@@ -1474,19 +1472,8 @@ var _ = Describe("Handle - Global Injection Disabled", func() {
 		Expect(corev1.AddToScheme(s)).To(Succeed())
 	})
 
-	AfterEach(func() {
-		if patch != nil {
-			patch.Reset()
-		}
-	})
-
 	It("should skip mutation when global injection is disabled", func() {
-		patch = gomonkey.ApplyFunc(utils.GetBoolValueFromEnv, func(key string, defaultValue bool) bool {
-			if key == common.EnvDisableInjection {
-				return true
-			}
-			return defaultValue
-		})
+		GinkgoT().Setenv(common.EnvDisableInjection, "true")
 
 		req := admission.Request{
 			AdmissionRequest: admissionv1.AdmissionRequest{

pkg/webhook/handler/mutating/mutating_suite_test.go

@@ -1,4 +1,20 @@
-package mutating_test
+/*
+Copyright 2026 The Fluid 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 mutating
 
 import (
 	"testing"

pkg/webhook/handler/mutating/webhook_test.go

@@ -0,0 +1,36 @@
+/*
+Copyright 2026 The Fluid 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 mutating
+
+import (
+	"github.com/fluid-cloudnative/fluid/pkg/common"
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("HandlerMap", func() {
+	It("should register a handler under WebhookSchedulePodPath", func() {
+		Expect(HandlerMap).To(HaveKey(common.WebhookSchedulePodPath))
+	})
+
+	It("should map WebhookSchedulePodPath to a *FluidMutatingHandler", func() {
+		handler, ok := HandlerMap[common.WebhookSchedulePodPath]
+		Expect(ok).To(BeTrue())
+		Expect(handler).NotTo(BeNil())
+		Expect(handler).To(BeAssignableToTypeOf(&FluidMutatingHandler{}))
+	})
+})