diff --git a/tests/README b/tests/README
index 971c94c..d5fc70a 100644
--- a/tests/README
+++ b/tests/README
@@ -191,11 +191,18 @@ library for your script to use.
    This takes three strings as parameter.  Based on <cmdline>,
    the todo_completion script is triggered in the current test
    environment and completions are compared with <completions>,
-   which should be a space-separated list.  Include a trailing
-   space in <cmdline> when you want to check new argument
-   completion; otherwise, completion is triggered with the
-   context of the last argument.  <message> should state what it
-   is testing.
+   which should be a space-separated list.  If any completion
+   contains whitespace, quote it; the entire <completions>
+   argument is eval()'ed.
+   Include a trailing space in <cmdline> when you want to check
+   new argument completion; otherwise, completion is triggered
+   with the context of the last argument. <message> should state
+   what it is testing.
+
+ - test_todo_custom_completion <completefunc> <message> <cmdline> <completions>
+
+   Same as above, but in addition allows to specify a custom
+   completion function.
 
  - test_tick [interval]
 
@@ -216,6 +223,13 @@ library for your script to use.
 	    'git-write-tree should be able to write an empty tree.' \
 	    'tree=$(git-write-tree)'
 
+ - test_expect_code <code> <message> <script>
+
+   This takes an exit status and two strings as parameter, and
+   evaluates the <script>.  If it yields <code>, test is
+   considered successful.  <message> should state what it is
+   testing.
+
  - test_expect_failure <message> <script>
 
    This is NOT the opposite of test_expect_success, but is used
diff --git a/tests/t6000-completion.sh b/tests/t6000-completion.sh
index cb1eccf..9403b8b 100755
--- a/tests/t6000-completion.sh
+++ b/tests/t6000-completion.sh
@@ -7,12 +7,16 @@ 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 $OPTIONS"
 test_todo_completion 'arguments beginning with a' 'todo.sh a' 'add a addto addm append app archive'
 test_todo_completion 'all options' 'todo.sh -' "$OPTIONS"
 test_todo_completion 'all actions after command action' 'todo.sh command ' "$ACTIONS"
+test_todo_completion 'all arguments after option' 'todo.sh -a ' "$ACTIONS $OPTIONS"
+test_todo_completion 'all arguments after options' 'todo.sh -a -p ' "$ACTIONS $OPTIONS"
+test_todo_completion 'all options after options' 'todo.sh -a -p -' "$OPTIONS"
+test_todo_completion 'nothing after action' 'todo.sh archive ' ''
 
 test_done
diff --git a/tests/t6030-completion-tasks.sh b/tests/t6030-completion-tasks.sh
new file mode 100755
index 0000000..8b344bb
--- /dev/null
+++ b/tests/t6030-completion-tasks.sh
@@ -0,0 +1,25 @@
+#!/bin/bash
+#
+
+test_description='Bash task number completion functionality
+
+This test checks todo_completion of a task number into the abbreviated task text.
+'
+. ./test-lib.sh
+
+cat > todo.txt <<EOF
+simple task
+notice the sunflowers +sunflowers @outside @garden +shared +landscape
+(B) smell the +roses flower @outside @outdoor +shared
+(C) 2012-02-28 @outside mow the lawn
+x 2012-02-21 +herbs @oriental buy spices
+x 2012-02-28 2012-02-21 +slack @home watch tv
+EOF
+test_todo_completion 'simple task' 'todo.sh list 1' '"1 # simple task"'
+test_todo_completion 'remove projects and contents from task' 'todo.sh list 2' '"2 # notice the sunflowers"'
+test_todo_completion 'keep priority' 'todo.sh list 3' '"3 # (B) smell the flower"'
+test_todo_completion 'keep priority and remove timestamp' 'todo.sh list 4' '"4 # (C) mow the lawn"'
+test_todo_completion 'keep done marker and remove done date' 'todo.sh list 5' '"5 # x buy spices"'
+test_todo_completion 'keep done marker and remove timestamp and done date' 'todo.sh list 6' '"6 # x watch tv"'
+
+test_done
diff --git a/tests/t6040-completion-files.sh b/tests/t6040-completion-files.sh
new file mode 100755
index 0000000..ad43054
--- /dev/null
+++ b/tests/t6040-completion-files.sh
@@ -0,0 +1,21 @@
+#!/bin/bash
+#
+
+test_description='Bash todo file completion functionality
+
+This test checks todo_completion of files in TODO_DIR.
+'
+. ./test-lib.sh
+
+> dummy.txt
+readonly FILES='done.txt dummy.txt report.txt todo.txt'
+test_todo_completion 'all files after addto' 'todo.sh addto ' "$FILES"
+test_todo_completion 'files beginning with d after addto' 'todo.sh addto d' 'done.txt dummy.txt'
+test_todo_completion 'all files after listfile' 'todo.sh listfile ' "$FILES"
+test_todo_completion 'all files after lf' 'todo.sh -v lf ' "$FILES"
+test_todo_completion 'nothing after move' 'todo.sh move ' ''
+test_todo_completion 'all files after move ITEM#' 'todo.sh move 1 ' "$FILES"
+test_todo_completion 'all files after mv ITEM#' 'todo.sh mv 1 ' "$FILES"
+test_todo_completion 'all files after move ITEM# DEST' 'todo.sh move 1 todo.sh ' "$FILES"
+
+test_done
diff --git a/tests/t6050-completion-addons.sh b/tests/t6050-completion-addons.sh
new file mode 100755
index 0000000..ef38819
--- /dev/null
+++ b/tests/t6050-completion-addons.sh
@@ -0,0 +1,74 @@
+#!/bin/bash
+#
+
+test_description='Bash add-on action completion functionality
+
+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 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'
+makeCustomActions()
+{
+    set -e
+    mkdir "${1:?}"
+    for addon in $ADDONS
+    do
+        addonFile="${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
diff --git a/tests/t6080-completion-path.sh b/tests/t6080-completion-path.sh
new file mode 100755
index 0000000..efbea4c
--- /dev/null
+++ b/tests/t6080-completion-path.sh
@@ -0,0 +1,45 @@
+#!/bin/bash
+#
+
+test_description='Bash completion with different path functionality
+
+This test checks that todo_completion can use a different path to todo.sh when
+it is not accessible through PATH.
+'
+. ./test-lib.sh
+
+cat > todo.txt <<EOF
+(B) smell the +roses @outside @outdoor +shared
+notice the sunflowers +sunflowers @outside @garden +shared +landscape
+stop
+EOF
+
+mv bin/todo.sh bin/todo2.sh
+test_expect_success 'todo2.sh executable' 'todo2.sh list'
+
+# Define a second completion function that injects the different executable. In
+# real use, this would be installed via
+#   complete -F _todo2 todo2.sh
+_todo2()
+{
+    local _todo_sh='todo2.sh'
+    _todo "$@"
+}
+
+test_todo_custom_completion _todo2 'all todo2 contexts' 'todo2 list @' '@garden @outdoor @outside'
+
+
+
+# Remove the test environment's bin directory from the PATH, so that our test
+# executable must be launched with an explicit path.
+PATH=${PATH##"${PWD}/bin:"}
+test_expect_code 127 'todo2.sh executable not in PATH' 'todo2.sh'
+
+_todo2path()
+{
+    local _todo_sh='./bin/todo2.sh'
+    _todo "$@"
+}
+test_todo_custom_completion _todo2path 'all todo2 contexts' 'todo2 list @' '@garden @outdoor @outside'
+
+test_done
diff --git a/tests/t6090-completion-aliases.sh b/tests/t6090-completion-aliases.sh
new file mode 100755
index 0000000..e7ba802
--- /dev/null
+++ b/tests/t6090-completion-aliases.sh
@@ -0,0 +1,62 @@
+#!/bin/bash
+#
+
+test_description='Bash completion with different aliases functionality
+
+This test checks that todo_completion can use a different configuration
+when another todo.sh alias is defined that uses that configuration.
+'
+. ./test-lib.sh
+
+cat > todo.txt <<EOF
+(B) smell the +roses @outside @outdoor +shared
+notice the sunflowers +sunflowers @outside @garden +shared +landscape
+stop
+EOF
+cat > todo2.txt <<EOF
++herbs @oriental buy spices
++slack @home watch tv
+EOF
+
+cp todo.cfg todo2.cfg
+cat >> todo2.cfg <<'EOF'
+export TODO_FILE="$TODO_DIR/todo2.txt"
+EOF
+
+# Note: We cannot use aliases within the test framework, but functions are
+# equivalent and work fine.
+todo1()
+{
+    todo.sh "$@"
+}
+todo2()
+{
+    todo.sh -d "$HOME/todo2.cfg" "$@"
+}
+
+# Ensure that the test fixture works as planned.
+test_todo_session 'todo 1 and 2 contexts' <<EOF
+>>> todo1 listcon
+@garden
+@outdoor
+@outside
+
+>>> todo2 listcon
+@home
+@oriental
+EOF
+
+
+# Define a second completion function that injects the different configuration
+# file. In real use, this would be installed via
+#   complete -F _todo2 todo2
+_todo2()
+{
+    local _todo_sh='todo.sh -d "$HOME/todo2.cfg"'
+    _todo "$@"
+}
+
+test_todo_completion               'all todo1 contexts' 'todo1 list @' '@garden @outdoor @outside'
+test_todo_custom_completion _todo2 'all todo2 contexts' 'todo2 list @' '@home @oriental'
+
+test_done
diff --git a/tests/test-lib.sh b/tests/test-lib.sh
index 3e56af3..b3022dd 100644
--- a/tests/test-lib.sh
+++ b/tests/test-lib.sh
@@ -632,9 +632,11 @@ EOF
 	exit 0
 }
 
-test_todo_completion () {
-	test "$#" = 3 ||
-	error "bug in the test script: not 3 parameters to test_todo_completion"
+test_todo_custom_completion () {
+	test "$#" = 4 ||
+	error "bug in the test script: not 4 parameters to test_todo_custom_completion"
+	completeFunc=$1
+	shift
 	if ! test_skip "$@"
 	then
 		description=$1
@@ -653,11 +655,11 @@ test_todo_completion () {
 		IFS=' ' set -- $2
 		COMP_WORDS=("$@")
 		COMP_CWORD=$(($# - $offset))
-		IFS=' ' set -- $expected
+		IFS=' ' eval "set -- $expected"
 		EXPECT=("$@")
 
 		source "$TEST_DIRECTORY/../todo_completion"
-		_todo
+		$completeFunc
 		ret=$?
 		if [ "$ret" = 0 ]
 		then
@@ -684,6 +686,11 @@ $(test_cmp expect compreply)"
 	fi
 	echo >&3 ""
 }
+test_todo_completion () {
+	test "$#" = 3 ||
+	error "bug in the test script: not 3 parameters to test_todo_completion"
+	test_todo_custom_completion _todo "$@"
+}
 
 test_init_todo "$test"
 # Use -P to resolve symlinks in our working directory so that the pwd
diff --git a/todo.sh b/todo.sh
index 4c2a4d9..4837120 100755
--- a/todo.sh
+++ b/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
diff --git a/todo_completion b/todo_completion
index df1fd07..3f9d308 100644
--- a/todo_completion
+++ b/todo_completion
@@ -11,41 +11,38 @@ _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
         # "move ITEM# DEST [SRC]" has file arguments on positions 2 and 3.
-        completions=$(TODOTXT_VERBOSE=0 todo.sh command listfile)
+        completions=$(eval TODOTXT_VERBOSE=0 $_todo_sh command listfile)
     else
         case "$prev" in
             command)
                 completions=$COMMANDS;;
             addto|listfile|lf)
-                completions=$(TODOTXT_VERBOSE=0 todo.sh command listfile);;
-            -*) completions="$allCommands $OPTS";;
+                completions=$(eval TODOTXT_VERBOSE=0 $_todo_sh command listfile);;
+            -*) completions="$COMMANDS $(eval TODOTXT_VERBOSE=0 $_todo_sh command listaddons) $OPTS";;
             *)  case "$cur" in
-                    +*) completions=$(TODOTXT_VERBOSE=0 todo.sh command listproj)
+                    +*) completions=$(eval TODOTXT_VERBOSE=0 $_todo_sh command listproj)
                         COMPREPLY=( $( compgen -W "$completions" -- $cur ))
                         [ ${#COMPREPLY[@]} -gt 0 ] && return 0
                         # Fall back to projects extracted from done tasks.
-                        completions=$(TODOTXT_VERBOSE=0 TODOTXT_SOURCEVAR=\$DONE_FILE todo.sh command listproj)
+                        completions=$(eval 'TODOTXT_VERBOSE=0 TODOTXT_SOURCEVAR=\$DONE_FILE' $_todo_sh command listproj)
                         ;;
-                    @*) completions=$(TODOTXT_VERBOSE=0 todo.sh command listcon)
+                    @*) completions=$(eval TODOTXT_VERBOSE=0 $_todo_sh command listcon)
                         COMPREPLY=( $( compgen -W "$completions" -- $cur ))
                         [ ${#COMPREPLY[@]} -gt 0 ] && return 0
                         # Fall back to contexts extracted from done tasks.
-                        completions=$(TODOTXT_VERBOSE=0 TODOTXT_SOURCEVAR=\$DONE_FILE todo.sh command listcon)
+                        completions=$(eval 'TODOTXT_VERBOSE=0 TODOTXT_SOURCEVAR=\$DONE_FILE' $_todo_sh command listcon)
                         ;;
                     *)  if [[ "$cur" =~ ^[0-9]+$ ]]; then
                             # Remove the (padded) task number; we prepend the
@@ -60,8 +57,8 @@ _todo()
                             # Finally, limit the output to a single line just as
                             # a safety check of the ls action output.
                             local todo=$( \
-                                TODOTXT_VERBOSE=0 todo.sh -@ -+ -p -x command ls "^ *${cur} " | \
-                                sed -e 's/^ *[0-9]\+ //' -e 's/\((.) \)[0-9]\{2,4\}-[0-9]\{2\}-[0-9]\{2\} /\1/' \
+                                eval TODOTXT_VERBOSE=0 $_todo_sh '-@ -+ -p -x command ls "^ *${cur} "' | \
+                                sed -e 's/^ *[0-9]\{1,\} //' -e 's/\((.) \)[0-9]\{2,4\}-[0-9]\{2\}-[0-9]\{2\} /\1/' \
                                     -e 's/\([xX] \)\([0-9]\{2,4\}-[0-9]\{2\}-[0-9]\{2\} \)\{1,2\}/\1/' \
                                     -e 's/[[:space:]]*$//' \
                                     -e '1q' \
@@ -84,6 +81,27 @@ _todo()
     return 0
 }
 complete -F _todo todo.sh
+
 # If you define an alias (e.g. "t") to todo.sh, you need to explicitly enable
 # completion for it, too:
 #complete -F _todo t
+
+# If you have renamed the todo.sh executable, or if it is not accessible through
+# PATH, you need to add and use a wrapper completion function, like this:
+#_todoElsewhere()
+#{
+#    local _todo_sh='/path/to/todo2.sh'
+#    _todo "$@"
+#}
+#complete -F _todoElsewhere /path/to/todo2.sh
+
+# If you use aliases to use different configuration(s), you need to add and use
+# a wrapper completion function for each configuration if you want to complete
+# fron the actual configured task locations:
+#alias todo2='todo.sh -d "$HOME/todo2.cfg"'
+#_todo2()
+#{
+#    local _todo_sh='todo.sh -d "$HOME/todo2.cfg"'
+#    _todo "$@"
+#}
+#complete -F _todo2 todo2