test: add show_flag_test and document --show-keys in help

Author: SupananWC

contrib/external-tests/show_flag_test.sh

@@ -0,0 +1,28 @@
+#!/usr/bin/env bash
+# SPDX-License-Identifier: MIT
+# Small integration test: build `wg` and check that `wg show --help` mentions --show-keys
+set -euo pipefail
+
+REPO_ROOT="$(cd "$(dirname "$0")/../.." && pwd)"
+cd "$REPO_ROOT/src"
+
+echo "Building src/ (this may take a moment)..."
+make V=1 || { echo "Build failed"; exit 2; }
+
+WG_BIN="$REPO_ROOT/src/wg"
+if [ ! -x "$WG_BIN" ]; then
+  echo "wg binary not found at $WG_BIN" >&2
+  exit 3
+fi
+
+echo "Checking 'wg show --help' for --show-keys flag"
+HELP_OUT="$($WG_BIN show --help 2>&1 || true)"
+
+if echo "$HELP_OUT" | grep -q -- "--show-keys"; then
+  echo "OK: --show-keys documented in show help"
+  exit 0
+else
+  echo "FAIL: --show-keys not found in show help output:" >&2
+  echo "$HELP_OUT" >&2
+  exit 4
+fi

src/show.c

@@ -207,6 +207,7 @@ static const char *COMMAND_NAME;
 static void show_usage(void)
 {
 	fprintf(stderr, "Usage: %s %s { <interface> | all | interfaces } [public-key | private-key | listen-port | fwmark | peers | preshared-keys | endpoints | allowed-ips | latest-handshakes | transfer | persistent-keepalive | dump]\n", PROG_NAME, COMMAND_NAME);
+	fprintf(stderr, "Optional flags: --show-keys\n");
 }
 
 static void pretty_print(struct wgdevice *device)