arp: New completion, somewhat incomplete

completions/Makefile.am

@@ -16,6 +16,7 @@ bashcomp_DATA = 2to3 \
 		apt-get \
 		aptitude \
 		arch \
+		arp \
 		arping \
 		arpspoof \
 		asciidoc \

completions/arp

@@ -0,0 +1,59 @@
+# arp(8) completion                                 -*- shell-script -*-
+
+_arp()
+{
+    local cur prev words cword
+    _init_completion || return
+
+    case $prev in
+        --device|-!(-*)i)
+            _available_interfaces -a
+            return
+            ;;
+        --protocol|-!(-*)[Ap])
+            # TODO protocol/address family
+            return
+            ;;
+        --file|-!(-*)f)
+            _filedir
+            return
+            ;;
+        --hw-type|-!(-*)[Ht])
+            # TODO: parse from --help output?
+            COMPREPLY=( $( compgen -W 'ash ether ax25 netrom rose arcnet \
+                dlci fddi hippi irda x25 eui64' -- "$cur" ) )
+            return
+            ;;
+    esac
+
+    if [[ $cur == -* ]]; then
+        COMPREPLY=( $( compgen -W '$( _parse_help "$1" )' -- "$cur" ) )
+        return
+    fi
+
+    local args
+    _count_args "" "@(--device|--protocol|--file|--hw-type|-!(-*)[iApfHt])"
+    case $args in
+        1)
+            local ips=$( "$1" -an | sed -ne \
+                's/.*(\([0-9]\{1,3\}\(\.[0-9]\{1,3\}\)\{3\}\)).*/\1/p' )
+            COMPREPLY=( $( compgen -W '$ips' -- "$cur" ) )
+            ;;
+        2)
+            # TODO if -d mode: "pub"; if not -f mode: hw_addr
+            # TODO hw_addr is a configured interface with --use-device/-*D*
+            ;;
+        3)
+            # TODO netmask|pub|temp if -s mode
+            ;;
+        4)
+            # TODO netmask value if previous was "netmask"
+            ;;
+        5)
+            # TODO "pub" if 3rd was "netmask"
+            ;;
+    esac
+} &&
+complete -F _arp arp
+
+# ex: filetype=sh

test/t/Makefile.am

@@ -24,6 +24,7 @@ EXTRA_DIST = \
 	test_aptitude.py \
 	test_arch.py \
 	test_arping.py \
+	test_arp.py \
 	test_arpspoof.py \
 	test_asciidoc.py \
 	test_aspell.py \

test/t/test_arp.py

@@ -0,0 +1,20 @@
+import os
+
+import pytest
+
+
+class TestArp:
+
+    @pytest.mark.complete("arp ")
+    def test_1(self, completion):
+        assert completion.list
+
+    @pytest.mark.complete("arp -")
+    def test_2(self, completion):
+        assert completion.list
+
+    @pytest.mark.xfail(bool(os.environ.get("CI")),
+                       reason="Probably fails in CI")
+    @pytest.mark.complete("arp -d ")
+    def test_3(self, completion):
+        assert completion.list