JMS-34: App.Run() can now be run multiple times.

- Added a method for looking up commands
- Using some logic to make sure default flags are not added more than
  once

app.go

@@ -1,9 +1,9 @@
 package cli
 
 import (
-	"os"
-	"io/ioutil"
 	"fmt"
+	"io/ioutil"
+	"os"
 )
 
 type App struct {
@@ -32,13 +32,13 @@ func NewApp() *App {
 
 func (a *App) Run(arguments []string) {
 	// append help to commands
-	a.Commands = append(a.Commands, helpCommand)
-	// append version to flags
-	a.Flags = append(
-		a.Flags,
-		BoolFlag{"version", "print the version"},
-		helpFlag{"show help"},
-	)
+	if a.Command(helpCommand.Name) == nil {
+		a.Commands = append(a.Commands, helpCommand)
+	}
+
+	//append version/help flags
+	a.appendFlag(BoolFlag{"version", "print the version"})
+	a.appendFlag(helpFlag{"show help"})
 
 	// parse flags
 	set := flagSet(a.Name, a.Flags)
@@ -59,14 +59,39 @@ func (a *App) Run(arguments []string) {
 	args := context.Args()
 	if len(args) > 0 {
 		name := args[0]
-		for _, c := range a.Commands {
-			if c.HasName(name) {
-				c.Run(context)
-				return
-			}
+		c := a.Command(name)
+		if c != nil {
+			c.Run(context)
+			return
 		}
 	}
 
 	// Run default Action
 	a.Action(context)
 }
+
+func (a *App) Command(name string) *Command {
+	for _, c := range a.Commands {
+		if c.HasName(name) {
+			return &c
+		}
+	}
+
+	return nil
+}
+
+func (a *App) hasFlag(flag Flag) bool {
+	for _, f := range a.Flags {
+		if flag == f {
+			return true
+		}
+	}
+
+	return false
+}
+
+func (a *App) appendFlag(flag Flag) {
+	if !a.hasFlag(flag) {
+		a.Flags = append(a.Flags, flag)
+	}
+}

app_test.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"github.com/codegangsta/cli"
 	"os"
+	"testing"
 )
 
 func ExampleApp() {
@@ -22,3 +23,42 @@ func ExampleApp() {
 	// Output:
 	// Hello Jeremy
 }
+
+func TestApp_Run(t *testing.T) {
+	s := ""
+
+	app := cli.NewApp()
+	app.Action = func(c *cli.Context) {
+		s = s + c.Args()[0]
+	}
+
+	app.Run([]string{"command", "foo"})
+	app.Run([]string{"command", "bar"})
+	expect(t, s, "foobar")
+}
+
+var commandAppTests = []struct {
+	name     string
+	expected bool
+}{
+	{"foobar", true},
+	{"batbaz", true},
+	{"b", true},
+	{"f", true},
+	{"bat", false},
+	{"nothing", false},
+}
+
+func TestApp_Command(t *testing.T) {
+	app := cli.NewApp()
+	fooCommand := cli.Command{Name: "foobar", ShortName: "f"}
+	batCommand := cli.Command{Name: "batbaz", ShortName: "b"}
+	app.Commands = []cli.Command{
+		fooCommand,
+		batCommand,
+	}
+
+	for _, test := range commandAppTests {
+		expect(t, app.Command(test.name) != nil, test.expected)
+	}
+}