ENH: Better completion for custom add-ons via new listaddons command.

The todo_completion had the problem that it didn't consider the todo.cfg itself for the location of TODO_ACTIONS_DIR, it just tried the default location or a globally exported config value. With the injection of custom configuration now in place, we can actually delegate the listing to todo.sh itself.
The added built-in "listaddons" command is used for that; it may also be helpful for troubleshooting or to find out about available add-ons. (But the help / shorthelp commands offer more information.)

Additionally, completion is now more precise; only executable actions and no subdirs are listed now; this is also covered by the enhanced test.

The last bonus: The custom add-on actions are now only determined when there's actually completion of commands.

tests/t6000-completion.sh

@@ -7,7 +7,7 @@ This test checks basic todo_completion of actions and options
 '
 . ./test-lib.sh
 
-readonly ACTIONS='add a addto addm append app archive command del rm depri dp do help list ls listall lsa listcon lsc listfile lf listpri lsp listproj lsprj move mv prepend prep pri p replace report shorthelp'
+readonly ACTIONS='add a addto addm append app archive command del rm depri dp do help list ls listaddons listall lsa listcon lsc listfile lf listpri lsp listproj lsprj move mv prepend prep pri p replace report shorthelp'
 readonly OPTIONS='-@ -@@ -+ -++ -d -f -h -p -P -PP -a -n -t -v -vv -V -x'
 
 test_todo_completion 'all arguments' 'todo.sh ' "$ACTIONS $OPTIONS"

tests/t6050-completion-addons.sh

@@ -7,20 +7,68 @@ This test checks todo_completion of custom actions in .todo.actions.d
 '
 . ./test-lib.sh
 
-readonly ACTIONS='add a addto addm append app archive command del rm depri dp do help list ls listall lsa listcon lsc listfile lf listpri lsp listproj lsprj move mv prepend prep pri p replace report shorthelp'
+readonly ACTIONS='add a addto addm append app archive command del rm depri dp do help list ls listaddons listall lsa listcon lsc listfile lf listpri lsp listproj lsprj move mv prepend prep pri p replace report shorthelp'
 readonly OPTIONS='-@ -@@ -+ -++ -d -f -h -p -P -PP -a -n -t -v -vv -V -x'
 
 readonly ADDONS='bar baz foobar'
-mkdir "$HOME/.todo.actions.d"
+makeCustomActions()
+{
+    set -e
+    mkdir "${1:?}"
     for addon in $ADDONS
     do
-    > "$HOME/.todo.actions.d/$addon"
-    chmod +x "$HOME/.todo.actions.d/$addon"
+        addonFile="${1}/$addon"
+        > "$addonFile"
+        chmod +x "$addonFile"
     done
+
+    # Also create a subdirectory, to test that it is skipped.
+    mkdir "${1}/subdir"
+
+    # Also create a non-executable file, to test that it is skipped.
+    datafile="${1:?}/datafile"
+    > "$datafile"
+    chmod -x "$datafile"
+    [ -x "$datafile" ] && rm "$datafile"    # Some file systems may always make files executable; then, skip this check.
+
+    set +e
+}
+removeCustomActions()
+{
+    set -e
+    rmdir "${1}/subdir"
+    rm "${1:?}/"*
+    rmdir "$1"
+    set +e
+}
+
+#
+# Test resolution of the default TODO_ACTIONS_DIR.
+#
+makeCustomActions "$HOME/.todo.actions.d"
 test_todo_completion 'all arguments' 'todo.sh ' "$ACTIONS $ADDONS $OPTIONS"
 test_todo_completion 'all arguments after option' 'todo.sh -a ' "$ACTIONS $ADDONS $OPTIONS"
 test_todo_completion 'all arguments beginning with b' 'todo.sh b' 'bar baz'
 test_todo_completion 'all arguments beginning with f after options' 'todo.sh -a -v f' 'foobar'
 test_todo_completion 'nothing after addon action' 'todo.sh foobar ' ''
+removeCustomActions "$HOME/.todo.actions.d"
+
+#
+# Test resolution of an alternative TODO_ACTIONS_DIR.
+#
+mkdir  "$HOME/.todo"
+makeCustomActions "$HOME/.todo/actions"
+test_todo_completion 'all arguments with actions from .todo/actions/' 'todo.sh ' "$ACTIONS $ADDONS $OPTIONS"
+removeCustomActions "$HOME/.todo/actions"
+
+#
+# Test resolution of a configured TODO_ACTIONS_DIR.
+#
+makeCustomActions "$HOME/addons"
+cat >> todo.cfg <<'EOF'
+export TODO_ACTIONS_DIR="$HOME/addons"
+EOF
+test_todo_completion 'all arguments with actions from addons/' 'todo.sh ' "$ACTIONS $ADDONS $OPTIONS"
+removeCustomActions "$HOME/addons"
 
 test_done

todo.sh

@@ -57,6 +57,7 @@ shorthelp()
 		    help
 		    list|ls [TERM...]
 		    listall|lsa [TERM...]
+		    listaddons
 		    listcon|lsc
 		    listfile|lf [SRC [TERM...]]
 		    listpri|lsp [PRIORITIES] [TERM...]
@@ -219,6 +220,9 @@ help()
 		      TERM specified, lists entire todo.txt AND done.txt
 		      concatenated and sorted.
 
+		    listaddons
+		      Lists all added and overridden actions in the actions directory.
+
 		    listcon
 		    lsc
 		      Lists all the task contexts that start with the @ sign in todo.txt.
@@ -1300,6 +1304,18 @@ note: PRIORITY must be anywhere from A to Z."
     fi
     ;;
 
+"listaddons" )
+    if [ -d "$TODO_ACTIONS_DIR" ]; then
+        cd "$TODO_ACTIONS_DIR" || exit $?
+        for action in *
+        do
+            if [ -f "$action" -a -x "$action" ]; then
+                echo "$action"
+            fi
+        done
+    fi
+    ;;
+
 * )
     usage;;
 esac

todo_completion

@@ -11,18 +11,14 @@ _todo()
     local -r OPTS="-@ -@@ -+ -++ -d -f -h -p -P -PP -a -n -t -v -vv -V -x"
     local -r COMMANDS="\
         add a addto addm append app archive command del  \
-        rm depri dp do help list ls listall lsa listcon  \
+        rm depri dp do help list ls listaddons listall lsa listcon  \
         lsc listfile lf listpri lsp listproj lsprj move \
         mv prepend prep pri p replace report shorthelp"
 
-    # Add custom commands from add-ons, if installed.
-    # TODO: Filter for executable flag of files found in $TODO_ACTIONS_DIR.
-    local allCommands="$COMMANDS $('ls' "${TODO_ACTIONS_DIR:-$HOME/.todo.actions.d}/" 2>/dev/null)"
-
     local _todo_sh=${_todo_sh:-todo.sh}
     local completions
     if [ $COMP_CWORD -eq 1 ]; then
-        completions="$allCommands $OPTS"
+        completions="$COMMANDS $(eval TODOTXT_VERBOSE=0 $_todo_sh command listaddons) $OPTS"
     elif [[ $COMP_CWORD -gt 2 && ( \
         "${COMP_WORDS[COMP_CWORD-2]}" =~ ^(move|mv)$ || \
         "${COMP_WORDS[COMP_CWORD-3]}" =~ ^(move|mv)$ ) ]]; then
@@ -34,7 +30,7 @@ _todo()
                 completions=$COMMANDS;;
             addto|listfile|lf)
                 completions=$(eval TODOTXT_VERBOSE=0 $_todo_sh command listfile);;
-            -*) completions="$allCommands $OPTS";;
+            -*) completions="$COMMANDS $(eval TODOTXT_VERBOSE=0 $_todo_sh command listaddons) $OPTS";;
             *)  case "$cur" in
                     +*) completions=$(eval TODOTXT_VERBOSE=0 $_todo_sh command listproj)
                         COMPREPLY=( $( compgen -W "$completions" -- $cur ))