Add tests as requested.

context.go

@@ -186,23 +186,9 @@ func (a Args) First() string {
 	return a.Get(0)
 }
 
-// Last - Return the last argument, or else a blank string
-func (a Args) Last() string {
-	return a.Get(len(a) - 1)
-}
-
-// Head - Return the rest of the arguments (not the last one)
-// or else an empty string slice
-func (a Args) Head() Args {
-	if len(a) == 1 {
-		return a
-	}
-	return []string(a)[:len(a)-1]
-}
-
 // Tail returns the rest of the arguments (not the first one)
 // or else an empty string slice
-func (a Args) Tail() Args {
+func (a Args) Tail() []string {
 	if len(a) >= 2 {
 		return []string(a)[1:]
 	}

help.go

@@ -120,7 +120,7 @@ type helpPrinterCustom func(w io.Writer, templ string, data interface{}, customF
 // func(w io.Writer, templ string, data interface{})
 var HelpPrinter helpPrinter = printHelp
 
-// HelPrinterCustom is same as HelpPrinter but
+// HelpPrinterCustom is same as HelpPrinter but
 // takes a custom function for template function map.
 var HelpPrinterCustom helpPrinterCustom = printHelpCustom
 
@@ -134,18 +134,20 @@ func ShowAppHelpAndExit(c *Context, exitCode int) {
 }
 
 // ShowAppHelp is an action that displays the help.
-func ShowAppHelp(c *Context) error {
+func ShowAppHelp(c *Context) (err error) {
-	if c.App.CustomAppHelpTemplate != "" {
+	if c.App.CustomAppHelpTemplate == "" {
-		if c.App.ExtraInfo != nil {
-			HelpPrinterCustom(c.App.Writer, c.App.CustomAppHelpTemplate, c.App, map[string]interface{}{
-				"ExtraInfo": c.App.ExtraInfo,
-			})
-		} else {
-			HelpPrinter(c.App.Writer, c.App.CustomAppHelpTemplate, c.App)
-		}
-	} else {
 		HelpPrinter(c.App.Writer, AppHelpTemplate, c.App)
+		return
 	}
+	customAppData := func() map[string]interface{} {
+		if c.App.ExtraInfo == nil {
+			return nil
+		}
+		return map[string]interface{}{
+			"ExtraInfo": c.App.ExtraInfo,
+		}
+	}
+	HelpPrinterCustom(c.App.Writer, c.App.CustomAppHelpTemplate, c.App, customAppData())
 	return nil
 }
 
@@ -178,7 +180,7 @@ func ShowCommandHelp(ctx *Context, command string) error {
 	for _, c := range ctx.App.Commands {
 		if c.HasName(command) {
 			if c.CustomHelpTemplate != "" {
-				HelpPrinter(ctx.App.Writer, c.CustomHelpTemplate, c)
+				HelpPrinterCustom(ctx.App.Writer, c.CustomHelpTemplate, c, nil)
 			} else {
 				HelpPrinter(ctx.App.Writer, CommandHelpTemplate, c)
 			}

help_test.go

@@ -3,6 +3,8 @@ package cli
 import (
 	"bytes"
 	"flag"
+	"fmt"
+	"runtime"
 	"strings"
 	"testing"
 )
@@ -256,6 +258,49 @@ func TestShowSubcommandHelp_CommandAliases(t *testing.T) {
 	}
 }
 
+func TestShowCommandHelp_Customtemplate(t *testing.T) {
+	app := &App{
+		Commands: []Command{
+			{
+				Name: "frobbly",
+				Action: func(ctx *Context) error {
+					return nil
+				},
+				HelpName: "foo frobbly",
+				CustomHelpTemplate: `NAME:
+   {{.HelpName}} - {{.Usage}}
+
+USAGE:
+   {{.HelpName}} [FLAGS] TARGET [TARGET ...]
+
+FLAGS:
+  {{range .VisibleFlags}}{{.}}
+  {{end}}
+EXAMPLES:
+   1. Frobbly runs with this param locally.
+      $ {{.HelpName}} wobbly
+`,
+			},
+		},
+	}
+
+	output := &bytes.Buffer{}
+	app.Writer = output
+	app.Run([]string{"foo", "help", "frobbly"})
+
+	if strings.Contains(output.String(), "2. Frobbly runs without this param locally.") {
+		t.Errorf("expected output to exclude \"2. Frobbly runs without this param locally.\"; got: %q", output.String())
+	}
+
+	if !strings.Contains(output.String(), "1. Frobbly runs with this param locally.") {
+		t.Errorf("expected output to include \"1. Frobbly runs with this param locally.\"; got: %q", output.String())
+	}
+
+	if !strings.Contains(output.String(), "$ foo frobbly wobbly") {
+		t.Errorf("expected output to include \"$ foo frobbly wobbly\"; got: %q", output.String())
+	}
+}
+
 func TestShowAppHelp_HiddenCommand(t *testing.T) {
 	app := &App{
 		Commands: []Command{
@@ -287,3 +332,78 @@ func TestShowAppHelp_HiddenCommand(t *testing.T) {
 		t.Errorf("expected output to include \"frobbly\"; got: %q", output.String())
 	}
 }
+
+func TestShowAppHelp_CustomAppTemplate(t *testing.T) {
+	app := &App{
+		Commands: []Command{
+			{
+				Name: "frobbly",
+				Action: func(ctx *Context) error {
+					return nil
+				},
+			},
+			{
+				Name:   "secretfrob",
+				Hidden: true,
+				Action: func(ctx *Context) error {
+					return nil
+				},
+			},
+		},
+		ExtraInfo: func() map[string]string {
+			platform := fmt.Sprintf("OS: %s | Arch: %s", runtime.GOOS, runtime.GOARCH)
+			goruntime := fmt.Sprintf("Version: %s | CPUs: %d", runtime.Version(), runtime.NumCPU())
+			return map[string]string{
+				"PLATFORM": platform,
+				"RUNTIME":  goruntime,
+			}
+		},
+		CustomAppHelpTemplate: `NAME:
+  {{.Name}} - {{.Usage}}
+
+USAGE:
+  {{.Name}} {{if .VisibleFlags}}[FLAGS] {{end}}COMMAND{{if .VisibleFlags}} [COMMAND FLAGS | -h]{{end}} [ARGUMENTS...]
+
+COMMANDS:
+  {{range .VisibleCommands}}{{join .Names ", "}}{{ "\t" }}{{.Usage}}
+  {{end}}{{if .VisibleFlags}}
+GLOBAL FLAGS:
+  {{range .VisibleFlags}}{{.}}
+  {{end}}{{end}}
+VERSION:
+  2.0.0
+{{"\n"}}{{range $key, $value := ExtraInfo}}
+{{$key}}:
+  {{$value}}
+{{end}}`,
+	}
+
+	output := &bytes.Buffer{}
+	app.Writer = output
+	app.Run([]string{"app", "--help"})
+
+	if strings.Contains(output.String(), "secretfrob") {
+		t.Errorf("expected output to exclude \"secretfrob\"; got: %q", output.String())
+	}
+
+	if !strings.Contains(output.String(), "frobbly") {
+		t.Errorf("expected output to include \"frobbly\"; got: %q", output.String())
+	}
+
+	if !strings.Contains(output.String(), "PLATFORM:") ||
+		!strings.Contains(output.String(), "OS:") ||
+		!strings.Contains(output.String(), "Arch:") {
+		t.Errorf("expected output to include \"PLATFORM:, OS: and Arch:\"; got: %q", output.String())
+	}
+
+	if !strings.Contains(output.String(), "RUNTIME:") ||
+		!strings.Contains(output.String(), "Version:") ||
+		!strings.Contains(output.String(), "CPUs:") {
+		t.Errorf("expected output to include \"RUNTIME:, Version: and CPUs:\"; got: %q", output.String())
+	}
+
+	if !strings.Contains(output.String(), "VERSION:") ||
+		!strings.Contains(output.String(), "2.0.0") {
+		t.Errorf("expected output to include \"VERSION:, 2.0.0\"; got: %q", output.String())
+	}
+}