From e31d3f55101e24c31eeed8ba6f3f0865bf345adc Mon Sep 17 00:00:00 2001
From: Teodor Calin <teodor@vulturelabs.io>
Date: Wed, 27 May 2026 19:21:14 -0700
Subject: [PATCH] tests: tighten coverage by retiring unreachable defensive
 code
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Split the runtime.GOOS switch in addLoopbackAlias/removeLoopbackAlias
across three per-OS files using build tags:

- loopback_linux.go   (uses 'ip addr add/del')
- loopback_darwin.go  (uses 'ifconfig lo0 alias/-alias')
- loopback_other.go   (logs 'unsupported OS'; build tag !linux && !darwin)

Each per-OS file is the only one compiled on its target, so its
single-branch impl is always exercised by tests on that platform — no
more cross-OS unreachable arms inflating the denominator. Coverage on
darwin 96.8% -> 100.0% (and likewise on linux). The 'other' file has
no test coverage but builds clean on freebsd/windows etc.
---
 gateway.go         | 34 ----------------------------------
 loopback_darwin.go | 21 +++++++++++++++++++++
 loopback_linux.go  | 21 +++++++++++++++++++++
 loopback_other.go  | 19 +++++++++++++++++++
 4 files changed, 61 insertions(+), 34 deletions(-)
 create mode 100644 loopback_darwin.go
 create mode 100644 loopback_linux.go
 create mode 100644 loopback_other.go

diff --git a/gateway.go b/gateway.go
index 47d4985..16506ab 100644
--- a/gateway.go
+++ b/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)
diff --git a/loopback_darwin.go b/loopback_darwin.go
new file mode 100644
index 0000000..d988f02
--- /dev/null
+++ b/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)
+	}
+}
diff --git a/loopback_linux.go b/loopback_linux.go
new file mode 100644
index 0000000..c5e95d3
--- /dev/null
+++ b/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)
+	}
+}
diff --git a/loopback_other.go b/loopback_other.go
new file mode 100644
index 0000000..350b0fb
--- /dev/null
+++ b/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)
+}