From 4cc2bad36ed25559dd5b3de9edec78def518fd15 Mon Sep 17 00:00:00 2001
From: Richard Kovacs <kovacsricsi@gmail.com>
Date: Fri, 7 Oct 2016 16:38:36 +0200
Subject: [PATCH] Display error instead of just say command is incorrect

---
 app.go      |  4 ++--
 app_test.go | 17 +++++++++++++++++
 command.go  |  2 +-
 3 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/app.go b/app.go
index b9adf46..c3462b7 100644
--- a/app.go
+++ b/app.go
@@ -194,7 +194,7 @@ func (a *App) Run(arguments []string) (err error) {
 			HandleExitCoder(err)
 			return err
 		}
-		fmt.Fprintf(a.Writer, "%s\n\n", "Incorrect Usage.")
+		fmt.Fprintf(a.Writer, "%s %s\n\n", "Incorrect Usage.", err.Error())
 		ShowAppHelp(context)
 		return err
 	}
@@ -315,7 +315,7 @@ func (a *App) RunAsSubcommand(ctx *Context) (err error) {
 			HandleExitCoder(err)
 			return err
 		}
-		fmt.Fprintf(a.Writer, "%s\n\n", "Incorrect Usage.")
+		fmt.Fprintf(a.Writer, "%s %s\n\n", "Incorrect Usage.", err.Error())
 		ShowSubcommandHelp(context)
 		return err
 	}
diff --git a/app_test.go b/app_test.go
index 23c8aa6..e2e4087 100644
--- a/app_test.go
+++ b/app_test.go
@@ -252,6 +252,23 @@ func TestApp_RunAsSubcommandParseFlags(t *testing.T) {
 	expect(t, context.String("lang"), "spanish")
 }
 
+func TestApp_RunAsSubCommandIncorrectUsage(t *testing.T) {
+	a := App{
+		Flags: []Flag{
+			StringFlag{Name: "--foo"},
+		},
+		Writer: bytes.NewBufferString(""),
+	}
+
+	set := flag.NewFlagSet("", flag.ContinueOnError)
+	set.Parse([]string{"", "---foo"})
+	c := &Context{flagSet: set}
+
+	err := a.RunAsSubcommand(c)
+
+	expect(t, err, errors.New("bad flag syntax: ---foo"))
+}
+
 func TestApp_CommandWithFlagBeforeTerminator(t *testing.T) {
 	var parsedOption string
 	var args []string
diff --git a/command.go b/command.go
index 96253b6..d955249 100644
--- a/command.go
+++ b/command.go
@@ -138,7 +138,7 @@ func (c Command) Run(ctx *Context) (err error) {
 			HandleExitCoder(err)
 			return err
 		}
-		fmt.Fprintln(ctx.App.Writer, "Incorrect Usage.")
+		fmt.Fprintln(ctx.App.Writer, "Incorrect Usage:", err.Error())
 		fmt.Fprintln(ctx.App.Writer)
 		ShowCommandHelp(ctx, c.Name)
 		return err