feat: add arp cache unit testing

Signed-off-by: Tonghao Zhang <tonghao@bamaicloud.com>

Author: hao022

internal/procfs/net_arpcache_test.go

@@ -0,0 +1,117 @@
+// Copyright 2026 The HuaTuo 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 procfs
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestNetArpCache(t *testing.T) {
+	// Create temporary procfs
+	tempDir, err := os.MkdirTemp("", "procfs-test-")
+	require.NoError(t, err)
+	defer os.RemoveAll(tempDir)
+
+	arpDir := filepath.Join(tempDir, "proc/net/stat")
+	err = os.MkdirAll(arpDir, 0o755)
+	require.NoError(t, err)
+
+	arpCachePath := filepath.Join(arpDir, "arp_cache")
+
+	RootPrefix(tempDir)
+	defer RootPrefix("/")
+
+	t.Run("SuccessfulParse", func(t *testing.T) {
+		content := `entries allocs destroys hash_grows lookups hits dests
+		0a 0b 0c 0d 0e 0f 10`
+
+		err = os.WriteFile(arpCachePath, []byte(content), 0o600)
+		require.NoError(t, err)
+
+		stats, err := NetArpCache()
+		require.NoError(t, err)
+		require.NotNil(t, stats)
+		require.Len(t, stats.Stats, 7)
+		require.Equal(t, uint64(10), stats.Stats["entries"])
+		require.Equal(t, uint64(11), stats.Stats["allocs"])
+		require.Equal(t, uint64(12), stats.Stats["destroys"])
+		require.Equal(t, uint64(13), stats.Stats["hash_grows"])
+		require.Equal(t, uint64(14), stats.Stats["lookups"])
+		require.Equal(t, uint64(15), stats.Stats["hits"])
+		require.Equal(t, uint64(16), stats.Stats["dests"])
+	})
+
+	t.Run("FileNotFound", func(t *testing.T) {
+		_ = os.Remove(arpCachePath)
+
+		stats, err := NetArpCache()
+		require.Error(t, err)
+		require.Nil(t, stats)
+	})
+
+	t.Run("InvalidHex", func(t *testing.T) {
+		content := `entries
+		invalid`
+
+		err = os.WriteFile(arpCachePath, []byte(content), 0o600)
+		require.NoError(t, err)
+
+		stats, err := NetArpCache()
+		require.Error(t, err)
+		require.Contains(t, err.Error(), "invalid syntax")
+		require.Nil(t, stats)
+	})
+
+	t.Run("MissingSecondLine", func(t *testing.T) {
+		content := `entries allocs`
+
+		err = os.WriteFile(arpCachePath, []byte(content), 0o600)
+		require.NoError(t, err)
+
+		stats, err := NetArpCache()
+		require.NoError(t, err)
+		require.NotNil(t, stats)
+		require.Empty(t, stats.Stats)
+	})
+
+	t.Run("EmptyFile", func(t *testing.T) {
+		content := ``
+
+		err = os.WriteFile(arpCachePath, []byte(content), 0o600)
+		require.NoError(t, err)
+
+		stats, err := NetArpCache()
+		require.NoError(t, err)
+		require.NotNil(t, stats)
+		require.Empty(t, stats.Stats)
+	})
+
+	t.Run("MismatchedFieldsFewerValues", func(t *testing.T) {
+		content := `entries allocs destroys
+0a 0b`
+		err = os.WriteFile(arpCachePath, []byte(content), 0o600)
+		require.NoError(t, err)
+
+		stats, err := NetArpCache()
+		require.NoError(t, err)
+		require.Len(t, stats.Stats, 2)
+		require.Equal(t, uint64(10), stats.Stats["entries"])
+		require.Equal(t, uint64(11), stats.Stats["allocs"])
+	})
+}