test: add sysutil and cache tests

- Add RestartService tests (pkg/sysutil)
- Add decodeRedisValue and normalizeRedisValue tests (cache/l2.go)

internal/pkg/sysutil/restart_test.go

@@ -0,0 +1,28 @@
+package sysutil
+
+import (
+	"runtime"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestRestartService_NonLinux(t *testing.T) {
+	// On non-Linux systems, RestartService should return nil without exiting
+	if runtime.GOOS == "linux" {
+		t.Skip("Skipping non-Linux test on Linux")
+	}
+
+	err := RestartService()
+	require.NoError(t, err)
+}
+
+func TestRestartServiceAsync_NonLinux(t *testing.T) {
+	// On non-Linux systems, RestartServiceAsync should not panic
+	if runtime.GOOS == "linux" {
+		t.Skip("Skipping non-Linux test on Linux")
+	}
+
+	// Should not panic
+	RestartServiceAsync()
+}