separate args validation for better reuse

pkg/apis/componentconfig/validation/validation_pluginargs.go

@@ -18,6 +18,7 @@ package validation
 
 import (
 	"fmt"
+	utilerrors "k8s.io/apimachinery/pkg/util/errors"
 
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"sigs.k8s.io/descheduler/pkg/api"
@@ -26,20 +27,36 @@ import (
 
 // ValidateRemovePodsViolatingNodeTaintsArgs validates RemovePodsViolatingNodeTaints arguments
 func ValidateRemovePodsViolatingNodeTaintsArgs(args *componentconfig.RemovePodsViolatingNodeTaintsArgs) error {
-	return validateCommonArgs(args.Namespaces, args.LabelSelector)
+	return errorsAggregate(
+		validateNamespaceArgs(args.Namespaces),
+		validateLabelSelectorArgs(args.LabelSelector),
+	)
 }
 
 // ValidateRemoveFailedPodsArgs validates RemoveFailedPods arguments
 func ValidateRemoveFailedPodsArgs(args *componentconfig.RemoveFailedPodsArgs) error {
-	return validateCommonArgs(args.Namespaces, args.LabelSelector)
+	return errorsAggregate(
+		validateNamespaceArgs(args.Namespaces),
+		validateLabelSelectorArgs(args.LabelSelector),
+	)
 }
 
-func validateCommonArgs(namespaces *api.Namespaces, labelSelector *metav1.LabelSelector) error {
+// errorsAggregate converts all arg validation errors to a single error interface.
+// if no errors, it will return nil.
+func errorsAggregate(errors ...error) error {
+	return utilerrors.NewAggregate(errors)
+}
+
+func validateNamespaceArgs(namespaces *api.Namespaces) error {
 	// At most one of include/exclude can be set
 	if namespaces != nil && len(namespaces.Include) > 0 && len(namespaces.Exclude) > 0 {
 		return fmt.Errorf("only one of Include/Exclude namespaces can be set")
 	}
 
+	return nil
+}
+
+func validateLabelSelectorArgs(labelSelector *metav1.LabelSelector) error {
 	if labelSelector != nil {
 		if _, err := metav1.LabelSelectorAsSelector(labelSelector); err != nil {
 			return fmt.Errorf("failed to get label selectors from strategy's params: %+v", err)

pkg/apis/componentconfig/validation/validation_pluginargs_test.go

@@ -0,0 +1,85 @@
+/*
+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 validation
+
+import (
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"sigs.k8s.io/descheduler/pkg/api"
+	"sigs.k8s.io/descheduler/pkg/apis/componentconfig"
+	"testing"
+)
+
+func TestValidateRemovePodsViolatingNodeTaintsArgs(t *testing.T) {
+	testCases := []struct {
+		description string
+		args        *componentconfig.RemovePodsViolatingNodeTaintsArgs
+		expectError bool
+	}{
+		{
+			description: "valid namespace args, no errors",
+			args: &componentconfig.RemovePodsViolatingNodeTaintsArgs{
+				Namespaces: &api.Namespaces{
+					Include: []string{"default"},
+				},
+			},
+			expectError: false,
+		},
+		{
+			description: "invalid namespaces args, expects error",
+			args: &componentconfig.RemovePodsViolatingNodeTaintsArgs{
+				Namespaces: &api.Namespaces{
+					Include: []string{"default"},
+					Exclude: []string{"kube-system"},
+				},
+			},
+			expectError: true,
+		},
+		{
+			description: "valid label selector args, no errors",
+			args: &componentconfig.RemovePodsViolatingNodeTaintsArgs{
+				LabelSelector: &metav1.LabelSelector{
+					MatchLabels: map[string]string{"role.kubernetes.io/node": ""},
+				},
+			},
+			expectError: false,
+		},
+		{
+			description: "invalid label selector args, expects errors",
+			args: &componentconfig.RemovePodsViolatingNodeTaintsArgs{
+				LabelSelector: &metav1.LabelSelector{
+					MatchExpressions: []metav1.LabelSelectorRequirement{
+						{
+							Operator: metav1.LabelSelectorOpIn,
+						},
+					},
+				},
+			},
+			expectError: true,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.description, func(t *testing.T) {
+			err := ValidateRemovePodsViolatingNodeTaintsArgs(tc.args)
+
+			hasError := err != nil
+			if tc.expectError != hasError {
+				t.Error("unexpected arg validation behavior")
+			}
+		})
+	}
+}