pkg/proxy: move get kernel version out of ipvs proxier

Signed-off-by: Daman Arora <aroradaman@gmail.com>

pkg/util/kernel/version_test.go

@@ -0,0 +1,82 @@
+/*
+Copyright 2023 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 kernel
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"k8s.io/apimachinery/pkg/util/version"
+)
+
+func TestGetVersion(t *testing.T) {
+	testCases := []struct {
+		name         string
+		readFileFunc readFileFunc
+		expected     *version.Version
+		err          error
+	}{
+		{
+			name: "valid os-release file",
+			readFileFunc: func(_ string) ([]byte, error) {
+				return []byte("5.15.0-84-generic"), nil
+			},
+			expected: version.MajorMinor(5, 15),
+		},
+		{
+			name: "valid os-release file",
+			readFileFunc: func(_ string) ([]byte, error) {
+				return []byte("5.4.0-128-generic"), nil
+			},
+			expected: version.MajorMinor(5, 4),
+		},
+		{
+			name: "failed to read os-release file",
+			readFileFunc: func(_ string) ([]byte, error) {
+				return nil, errors.New("open /proc/sys/kernel/osrelease: failed to read file")
+			},
+			err:      errors.New("failed to read os-release file: open /proc/sys/kernel/osrelease: failed to read file"),
+			expected: nil,
+		},
+		{
+			name: "version not parsable",
+			readFileFunc: func(_ string) ([]byte, error) {
+				return []byte("5-15-0"), nil
+			},
+			err:      errors.New("failed to parse kernel version: illegal version string \"5-15-0\""),
+			expected: nil,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			kernelVersion, err := getVersion(tc.readFileFunc)
+
+			if tc.err != nil {
+				assert.Equal(t, tc.err.Error(), err.Error())
+				assert.Nil(t, kernelVersion)
+			} else {
+				assert.NoError(t, err)
+				assert.Equal(t, tc.expected.Major(), kernelVersion.Major())
+				assert.Equal(t, tc.expected.Minor(), kernelVersion.Minor())
+				assert.Equal(t, tc.expected.Patch(), kernelVersion.Patch())
+			}
+		})
+	}
+}