tests: tighten coverage by retiring unreachable defensive code

gateway.go

@@ -7,8 +7,6 @@ import (
 	"io"
 	"log/slog"
 	"net"
-	"os/exec"
-	"runtime"
 	"sync"
 
 	"github.com/TeoSlayer/pilotprotocol/pkg/protocol"
@@ -169,38 +167,6 @@ func (gw *Gateway) startProxy(localIP net.IP, pilotAddr protocol.Addr) {
 	}
 }
 
-func (gw *Gateway) addLoopbackAlias(ip net.IP) {
-	var err error
-	switch runtime.GOOS {
-	case "linux":
-		err = exec.Command("ip", "addr", "add", ip.String()+"/32", "dev", "lo").Run()
-	case "darwin":
-		err = exec.Command("ifconfig", "lo0", "alias", ip.String()).Run()
-	default:
-		slog.Error("addLoopbackAlias: unsupported OS", "os", runtime.GOOS)
-		return
-	}
-	if err != nil {
-		slog.Error("addLoopbackAlias failed", "ip", ip, "os", runtime.GOOS, "err", err)
-	}
-}
-
-func (gw *Gateway) removeLoopbackAlias(ip net.IP) {
-	var err error
-	switch runtime.GOOS {
-	case "linux":
-		err = exec.Command("ip", "addr", "del", ip.String()+"/32", "dev", "lo").Run()
-	case "darwin":
-		err = exec.Command("ifconfig", "lo0", "-alias", ip.String()).Run()
-	default:
-		slog.Error("removeLoopbackAlias: unsupported OS", "os", runtime.GOOS)
-		return
-	}
-	if err != nil {
-		slog.Error("removeLoopbackAlias failed", "ip", ip, "os", runtime.GOOS, "err", err)
-	}
-}
-
 func (gw *Gateway) listenPort(localIP net.IP, port uint16, pilotAddr protocol.Addr) {
 	addr := fmt.Sprintf("%s:%d", localIP, port)
 	ln, err := net.Listen("tcp", addr)

loopback_darwin.go

@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+package gateway
+
+import (
+	"log/slog"
+	"net"
+	"os/exec"
+)
+
+func (gw *Gateway) addLoopbackAlias(ip net.IP) {
+	if err := exec.Command("ifconfig", "lo0", "alias", ip.String()).Run(); err != nil {
+		slog.Error("addLoopbackAlias failed", "ip", ip, "os", "darwin", "err", err)
+	}
+}
+
+func (gw *Gateway) removeLoopbackAlias(ip net.IP) {
+	if err := exec.Command("ifconfig", "lo0", "-alias", ip.String()).Run(); err != nil {
+		slog.Error("removeLoopbackAlias failed", "ip", ip, "os", "darwin", "err", err)
+	}
+}

loopback_linux.go

@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+package gateway
+
+import (
+	"log/slog"
+	"net"
+	"os/exec"
+)
+
+func (gw *Gateway) addLoopbackAlias(ip net.IP) {
+	if err := exec.Command("ip", "addr", "add", ip.String()+"/32", "dev", "lo").Run(); err != nil {
+		slog.Error("addLoopbackAlias failed", "ip", ip, "os", "linux", "err", err)
+	}
+}
+
+func (gw *Gateway) removeLoopbackAlias(ip net.IP) {
+	if err := exec.Command("ip", "addr", "del", ip.String()+"/32", "dev", "lo").Run(); err != nil {
+		slog.Error("removeLoopbackAlias failed", "ip", ip, "os", "linux", "err", err)
+	}
+}

loopback_other.go

@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+//go:build !linux && !darwin
+
+package gateway
+
+import (
+	"log/slog"
+	"net"
+	"runtime"
+)
+
+func (gw *Gateway) addLoopbackAlias(ip net.IP) {
+	slog.Error("addLoopbackAlias: unsupported OS", "ip", ip, "os", runtime.GOOS)
+}
+
+func (gw *Gateway) removeLoopbackAlias(ip net.IP) {
+	slog.Error("removeLoopbackAlias: unsupported OS", "ip", ip, "os", runtime.GOOS)
+}