From 0113f56d1094e8565f6d1ad10526865fd61d57aa Mon Sep 17 00:00:00 2001
From: Jesse Szwedko <jesse.szwedko@gmail.com>
Date: Sat, 12 Nov 2016 13:37:07 -0800
Subject: [PATCH] If no action is specified on the command or app, print the
 help documentation

Rather than panic'ing or displaying an opaque error message about the
signature which is more confusing to the end user.

Fixes #562
---
 app.go      |  4 ++++
 app_test.go | 43 +++++++++++++++++++++++++++++++++++++++++++
 command.go  |  4 ++++
 help.go     |  2 +-
 4 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/app.go b/app.go
index 26cf09a..a90a4df 100644
--- a/app.go
+++ b/app.go
@@ -242,6 +242,10 @@ func (a *App) Run(arguments []string) (err error) {
 		}
 	}
 
+	if a.Action == nil {
+		a.Action = helpCommand.Action
+	}
+
 	// Run default Action
 	err = HandleAction(a.Action, context)
 
diff --git a/app_test.go b/app_test.go
index 40a598d..711de47 100644
--- a/app_test.go
+++ b/app_test.go
@@ -178,6 +178,49 @@ func ExampleApp_Run_commandHelp() {
 	//    This is how we describe describeit the function
 }
 
+func ExampleApp_Run_noAction() {
+	app := App{}
+	app.Name = "greet"
+	app.Run([]string{"greet"})
+	// Output:
+	// NAME:
+	//    greet
+	//
+	// USAGE:
+	//     [global options] command [command options] [arguments...]
+	//
+	// COMMANDS:
+	//      help, h  Shows a list of commands or help for one command
+	//
+	// GLOBAL OPTIONS:
+	//    --help, -h     show help
+	//    --version, -v  print the version
+}
+
+func ExampleApp_Run_subcommandNoAction() {
+	app := App{}
+	app.Name = "greet"
+	app.Commands = []Command{
+		{
+			Name:        "describeit",
+			Aliases:     []string{"d"},
+			Usage:       "use it to see a description",
+			Description: "This is how we describe describeit the function",
+		},
+	}
+	app.Run([]string{"greet", "describeit"})
+	// Output:
+	// NAME:
+	//     describeit - use it to see a description
+	//
+	// USAGE:
+	//     describeit [arguments...]
+	//
+	// DESCRIPTION:
+	//    This is how we describe describeit the function
+
+}
+
 func ExampleApp_Run_bashComplete() {
 	// set args for examples sake
 	os.Args = []string{"greet", "--generate-bash-completion"}
diff --git a/command.go b/command.go
index d955249..8f1a215 100644
--- a/command.go
+++ b/command.go
@@ -187,6 +187,10 @@ func (c Command) Run(ctx *Context) (err error) {
 		}
 	}
 
+	if c.Action == nil {
+		c.Action = helpSubcommand.Action
+	}
+
 	context.Command = c
 	err = HandleAction(c.Action, context)
 
diff --git a/help.go b/help.go
index 515f744..5ee11a6 100644
--- a/help.go
+++ b/help.go
@@ -13,7 +13,7 @@ import (
 // cli.go uses text/template to render templates. You can
 // render custom help text by setting this variable.
 var AppHelpTemplate = `NAME:
-   {{.Name}} - {{.Usage}}
+   {{.Name}}{{if .Usage}} - {{.Usage}}{{end}}
 
 USAGE:
    {{if .UsageText}}{{.UsageText}}{{else}}{{.HelpName}} {{if .VisibleFlags}}[global options]{{end}}{{if .Commands}} command [command options]{{end}} {{if .ArgsUsage}}{{.ArgsUsage}}{{else}}[arguments...]{{end}}{{end}}{{if .Version}}{{if not .HideVersion}}