ENH: Print usage help for all passed actions.

Extend the support for specific usage help to built-in actions.

tests/t2110-help-action.sh

@@ -0,0 +1,66 @@
+#!/bin/bash
+
+test_description='built-in actions help functionality
+
+This test checks listing the usage help of a built-in action.
+'
+. ./test-lib.sh
+
+test_todo_session 'nonexisting action help' <<'EOF'
+>>> todo.sh help doesnotexist
+TODO: No action "doesnotexist" exists.
+=== 1
+
+>>> todo.sh help hel
+TODO: No action "hel" exists.
+=== 1
+
+>>> todo.sh help h
+TODO: No action "h" exists.
+=== 1
+EOF
+
+test_todo_session 'single action help' <<'EOF'
+>>> todo.sh help shorthelp
+    shorthelp
+      List the one-line usage of all built-in and add-on actions.
+\
+EOF
+
+test_todo_session 'multiple actions help' <<'EOF'
+>>> todo.sh help shorthelp append
+    shorthelp
+      List the one-line usage of all built-in and add-on actions.
+\
+    append ITEM# "TEXT TO APPEND"
+    app ITEM# "TEXT TO APPEND"
+      Adds TEXT TO APPEND to the end of the task on line ITEM#.
+      Quotes optional.
+\
+EOF
+
+test_todo_session 'short and long form of action help' <<'EOF'
+>>> todo.sh help append
+    append ITEM# "TEXT TO APPEND"
+    app ITEM# "TEXT TO APPEND"
+      Adds TEXT TO APPEND to the end of the task on line ITEM#.
+      Quotes optional.
+\
+
+>>> todo.sh help app
+    app ITEM# "TEXT TO APPEND"
+      Adds TEXT TO APPEND to the end of the task on line ITEM#.
+      Quotes optional.
+\
+EOF
+
+test_todo_session 'mixed existing and nonexisting action help' <<'EOF'
+>>> todo.sh help shorthelp doesnotexist list
+    shorthelp
+      List the one-line usage of all built-in and add-on actions.
+\
+TODO: No action "doesnotexist" exists.
+=== 1
+EOF
+
+test_done

tests/t8020-actions-help.sh

@@ -1,6 +1,6 @@
 #!/bin/bash
 
-test_description='actions help functionality
+test_description='custom actions help functionality
 
 This test checks listing the usage help of a custom action.
 '
@@ -9,12 +9,13 @@ This test checks listing the usage help of a custom action.
 
 test_todo_session 'custom action help with no custom action directory' <<'EOF'
 >>> todo.sh help foo
-TODO: No actions directory exists.
+TODO: No action "foo" exists.
 === 1
 EOF
 
 make_action "foo"
 make_action "bar"
+make_action "ls"
 make_action "quux"
 
 test_todo_session 'custom action help' <<'EOF'
@@ -41,15 +42,35 @@ EOF
 
 test_todo_session 'nonexisting action help' <<'EOF'
 >>> todo.sh help doesnotexist
-TODO: No add-on action "doesnotexist" exists.
+TODO: No action "doesnotexist" exists.
 === 1
 
 >>> todo.sh help foo doesnotexist bar
     foo ITEM#[, ITEM#, ...] [TERM...]
       This custom action does foo.
 \
-TODO: No add-on action "doesnotexist" exists.
+TODO: No action "doesnotexist" exists.
 === 1
 EOF
 
+test_todo_session 'mixed built-in and custom actions help' <<'EOF'
+>>> todo.sh help foo shorthelp bar
+    foo ITEM#[, ITEM#, ...] [TERM...]
+      This custom action does foo.
+\
+    shorthelp
+      List the one-line usage of all built-in and add-on actions.
+\
+    bar ITEM#[, ITEM#, ...] [TERM...]
+      This custom action does bar.
+\
+EOF
+
+test_todo_session 'custom override of built-in action help' <<'EOF'
+>>> todo.sh help ls
+    ls ITEM#[, ITEM#, ...] [TERM...]
+      This custom action does ls.
+\
+EOF
+
 test_done

todo.sh

@@ -54,7 +54,7 @@ shorthelp()
 		    del|rm ITEM# [TERM]
 		    depri|dp ITEM#[, ITEM#, ITEM#, ...]
 		    do ITEM#[, ITEM#, ITEM#, ...]
-		    help
+		    help [ACTION...]
 		    list|ls [TERM...]
 		    listall|lsa [TERM...]
 		    listaddons
@@ -154,6 +154,13 @@ help()
 
 
 	EndVerboseHelp
+        actionsHelp
+        addonHelp
+    exit 1
+}
+
+actionsHelp()
+{
     cat <<-EndActionsHelp
 		  Built-in Actions:
 		    add "THING I NEED TO DO +project @context"
@@ -200,8 +207,9 @@ help()
 		    do ITEM#[, ITEM#, ITEM#, ...]
 		      Marks task(s) on line ITEM# as done in todo.txt.
 
-		    help
+		    help [ACTION...]
-		      Display this help message.
+		      Display help about usage, options, built-in and add-on actions,
+		      or just the usage help for the passed ACTION(s).
 
 		    list [TERM...]
 		    ls [TERM...]
@@ -278,9 +286,6 @@ help()
 		      List the one-line usage of all built-in and add-on actions.
 
 	EndActionsHelp
-
-        addonHelp
-    exit 1
 }
 
 addonHelp()
@@ -302,21 +307,23 @@ addonHelp()
     fi
 }
 
-addonUsage()
+actionUsage()
 {
-    if [ -d "$TODO_ACTIONS_DIR" ]; then
     for actionName
     do
         action="${TODO_ACTIONS_DIR}/${actionName}"
         if [ -f "$action" -a -x "$action" ]; then
             "$action" usage
         else
-                die "TODO: No add-on action \"${actionName}\" exists."
+            builtinActionUsage=$(actionsHelp | sed -ne "/^    ${actionName//\//\\/}\\( \\|\$\\)/,/^\$/p")
+            if [ "$builtinActionUsage" ]; then
+                echo "$builtinActionUsage"
+                echo
+            else
+                die "TODO: No action \"${actionName}\" exists."
+            fi
         fi
     done
-    else
-        die "TODO: No actions directory exists."
-    fi
 }
 
 die()
@@ -1095,7 +1102,7 @@ case $action in
     shift  ## Was help; new $1 is first help topic / action name
     if [ $# -gt 0 ]; then
         # Don't use PAGER here; we don't expect much usage output from one / few actions.
-        addonUsage "$@"
+        actionUsage "$@"
     else
         if [ -t 1 ] ; then # STDOUT is a TTY
             if which "${PAGER:-less}" >/dev/null 2>&1; then