feat(env): complete commands and variable assignments

Refs #1111

Co-authored-by: Koichi Murase <[email protected]>

bash_completion

@@ -2991,7 +2991,7 @@ _comp_complete_longopt()
 # makeinfo and texi2dvi are defined elsewhere.
 complete -F _comp_complete_longopt \
     a2ps awk base64 bash bc bison cat chroot colordiff cp \
-    csplit cut date df diff dir du enscript env expand fmt fold gperf \
+    csplit cut date df diff dir du enscript expand fmt fold gperf \
     grep grub head irb ld ldd less ln ls m4 mkdir mkfifo mknod \
     mv netstat nl nm objcopy objdump od paste pr ptx readelf rm rmdir \
     sed seq shar sort split strip sum tac tail tee \

completions/Makefile.am

@@ -100,6 +100,7 @@ bashcomp_DATA = 2to3 \
 		ebtables \
 		ecryptfs-migrate-home \
 		_eject \
+		env \
 		eog \
 		ether-wake \
 		evince \

completions/env

@@ -0,0 +1,49 @@
+# bash completion for env(1)                              -*- shell-script -*-
+
+_comp_cmd_env()
+{
+    local cur prev words cword was_split comp_args
+    _comp_initialize -s -- "$@" || return
+
+    local i noargopts='!(-*|*[uCS]*)'
+    for ((i = 1; i <= cword; i++)); do
+        if [[ ${words[i]} != -* && ${words[i]} != *=* ]]; then
+            _comp_command_offset $i
+            return
+        fi
+        # shellcheck disable=SC2254
+        [[ ${words[i]} == @(--@(unset|chdir|split-string)|-${noargopts}[uCS]) ]] &&
+            ((i++))
+    done
+
+    # shellcheck disable=SC2254
+    case "$prev" in
+        --unset | -${noargopts}u)
+            _comp_compgen -- -A variable
+            return
+            ;;
+        --chdir | -${noargopts}C)
+            _comp_compgen_filedir -d
+            return
+            ;;
+        --split-string | -${noargopts}S)
+            return
+            ;;
+        --block-signal | --default-signal | --ignore-signal)
+            # TODO signals, but only if completing with a =SIG
+            ;;
+    esac
+
+    [[ $was_split ]] && return
+
+    _comp_variable_assignments "$cur" && return
+
+    if [[ $cur == -* ]]; then
+        _comp_compgen_help || _comp_compgen_usage
+        [[ ${COMPREPLY-} == *= ]] && compopt -o nospace
+        return
+    fi
+} &&
+    complete -F _comp_cmd_env env
+
+# ex: filetype=sh

test/t/test_env.py

@@ -1,7 +1,31 @@
 import pytest
 
+from conftest import assert_complete
+
 
 class TestEnv:
     @pytest.mark.complete("env --", require_longopt=True)
     def test_1(self, completion):
         assert completion
+
+    @pytest.mark.complete("env __unknown_variable__=")
+    def test_unknown_variable_falls_back_to_filedir(self, completion):
+        assert "shared/" in completion
+
+    @pytest.mark.complete("env LANG=", xfail="! locale -a &>/dev/null")
+    def test_lang_envvar(self, completion):
+        assert any(x == "C" or x.startswith("C.") for x in completion)
+
+    @pytest.mark.parametrize(
+        "opts",
+        [
+            "",
+            "foo=bar",
+            "--debug",
+            "foo=bar --debug",
+            "--debug foo=bar",
+        ],
+    )
+    def test_command(self, bash, opts):
+        completion = assert_complete(bash, "env %s s" % opts)
+        assert completion == "h" or "sh" in completion