Merge pull request #653 from urfave/master

Merging master into v1

.travis.yml

@@ -1,28 +1,17 @@
 language: go
-
 sudo: false
+dist: trusty
+osx_image: xcode8.3
+go: 1.8.x
+
+os:
+- linux
+- osx
 
 cache:
   directories:
   - node_modules
 
-go:
-- 1.6.x
-- 1.7.x
-- 1.8.x
-- master
-
-matrix:
-  allow_failures:
-  - go: master
-  include:
-  - go: 1.6.x
-    os: osx
-  - go: 1.7.x
-    os: osx
-  - go: 1.8.x
-    os: osx
-
 before_script:
 - go get github.com/urfave/gfmrun/... || true
 - go get golang.org/x/tools/cmd/goimports

app.go

@@ -85,6 +85,12 @@ type App struct {
 	ErrWriter io.Writer
 	// Other custom info
 	Metadata map[string]interface{}
+	// Carries a function which returns app specific info.
+	ExtraInfo func() map[string]string
+	// CustomAppHelpTemplate the text template for app help topic.
+	// cli.go uses text/template to render templates. You can
+	// render custom help text by setting this variable.
+	CustomAppHelpTemplate string
 
 	didSetup bool
 }
@@ -234,7 +240,6 @@ func (a *App) Run(arguments []string) (err error) {
 	if a.Before != nil {
 		beforeErr := a.Before(context)
 		if beforeErr != nil {
-			fmt.Fprintf(a.Writer, "%v\n\n", beforeErr)
 			ShowAppHelp(context)
 			HandleExitCoder(beforeErr)
 			err = beforeErr

app_test.go

@@ -1520,6 +1520,63 @@ func TestApp_OnUsageError_WithWrongFlagValue_ForSubcommand(t *testing.T) {
 	}
 }
 
+// A custom flag that conforms to the relevant interfaces, but has none of the
+// fields that the other flag types do.
+type customBoolFlag struct {
+	Nombre string
+}
+
+// Don't use the normal FlagStringer
+func (c *customBoolFlag) String() string {
+	return "***" + c.Nombre + "***"
+}
+
+func (c *customBoolFlag) GetName() string {
+	return c.Nombre
+}
+
+func (c *customBoolFlag) Apply(set *flag.FlagSet) {
+	set.String(c.Nombre, c.Nombre, "")
+}
+
+func TestCustomFlagsUnused(t *testing.T) {
+	app := NewApp()
+	app.Flags = []Flag{&customBoolFlag{"custom"}}
+
+	err := app.Run([]string{"foo"})
+	if err != nil {
+		t.Errorf("Run returned unexpected error: %v", err)
+	}
+}
+
+func TestCustomFlagsUsed(t *testing.T) {
+	app := NewApp()
+	app.Flags = []Flag{&customBoolFlag{"custom"}}
+
+	err := app.Run([]string{"foo", "--custom=bar"})
+	if err != nil {
+		t.Errorf("Run returned unexpected error: %v", err)
+	}
+}
+
+func TestCustomHelpVersionFlags(t *testing.T) {
+	app := NewApp()
+
+	// Be sure to reset the global flags
+	defer func(helpFlag Flag, versionFlag Flag) {
+		HelpFlag = helpFlag
+		VersionFlag = versionFlag
+	}(HelpFlag, VersionFlag)
+
+	HelpFlag = &customBoolFlag{"help-custom"}
+	VersionFlag = &customBoolFlag{"version-custom"}
+
+	err := app.Run([]string{"foo", "--help-custom=bar"})
+	if err != nil {
+		t.Errorf("Run returned unexpected error: %v", err)
+	}
+}
+
 func TestHandleAction_WithNonFuncAction(t *testing.T) {
 	app := NewApp()
 	app.Action = 42
@@ -1642,7 +1699,7 @@ func TestShellCompletionForIncompleteFlags(t *testing.T) {
 
 		for _, flag := range ctx.App.Flags {
 			for _, name := range strings.Split(flag.GetName(), ",") {
-				if name == BashCompletionFlag.Name {
+				if name == BashCompletionFlag.GetName() {
 					continue
 				}
 
@@ -1659,7 +1716,7 @@ func TestShellCompletionForIncompleteFlags(t *testing.T) {
 	app.Action = func(ctx *Context) error {
 		return fmt.Errorf("should not get here")
 	}
-	err := app.Run([]string{"", "--test-completion", "--" + BashCompletionFlag.Name})
+	err := app.Run([]string{"", "--test-completion", "--" + BashCompletionFlag.GetName()})
 	if err != nil {
 		t.Errorf("app should not return an error: %s", err)
 	}

appveyor.yml

@@ -1,14 +1,16 @@
 version: "{build}"
 
-os: Windows Server 2012 R2
+os: Windows Server 2016
+
+image: Visual Studio 2017
 
 clone_folder: c:\gopath\src\github.com\urfave\cli
 
 environment:
   GOPATH: C:\gopath
-  GOVERSION: 1.6
+  GOVERSION: 1.8.x
-  PYTHON: C:\Python27-x64
+  PYTHON: C:\Python36-x64
-  PYTHON_VERSION: 2.7.x
+  PYTHON_VERSION: 3.6.x
   PYTHON_ARCH: 64
 
 install:

autocomplete/bash_autocomplete

@@ -12,3 +12,5 @@ _cli_bash_autocomplete() {
 }
 
 complete -F _cli_bash_autocomplete $PROG
+
+unset PROG

cli.go

@@ -12,6 +12,7 @@
 //     app.Usage = "say a greeting"
 //     app.Action = func(c *cli.Context) error {
 //       println("Greetings")
+//       return nil
 //     }
 //
 //     app.Run(os.Args)

command.go

@@ -59,6 +59,11 @@ type Command struct {
 	// Full name of command for help, defaults to full command name, including parent commands.
 	HelpName        string
 	commandNamePath []string
+
+	// CustomHelpTemplate the text template for the command help topic.
+	// cli.go uses text/template to render templates. You can
+	// render custom help text by setting this variable.
+	CustomHelpTemplate string
 }
 
 type CommandsByName []Command
@@ -154,19 +159,20 @@ func (c Command) Run(ctx *Context) (err error) {
 	}
 
 	context := NewContext(ctx.App, set, ctx)
+	context.Command = c
 	if checkCommandCompletions(context, c.Name) {
 		return nil
 	}
 
 	if err != nil {
 		if c.OnUsageError != nil {
-			err := c.OnUsageError(ctx, err, false)
+			err := c.OnUsageError(context, err, false)
 			HandleExitCoder(err)
 			return err
 		}
-		fmt.Fprintln(ctx.App.Writer, "Incorrect Usage:", err.Error())
+		fmt.Fprintln(context.App.Writer, "Incorrect Usage:", err.Error())
-		fmt.Fprintln(ctx.App.Writer)
+		fmt.Fprintln(context.App.Writer)
-		ShowCommandHelp(ctx, c.Name)
+		ShowCommandHelp(context, c.Name)
 		return err
 	}
 
@@ -191,9 +197,7 @@ func (c Command) Run(ctx *Context) (err error) {
 	if c.Before != nil {
 		err = c.Before(context)
 		if err != nil {
-			fmt.Fprintln(ctx.App.Writer, err)
+			ShowCommandHelp(context, c.Name)
-			fmt.Fprintln(ctx.App.Writer)
-			ShowCommandHelp(ctx, c.Name)
 			HandleExitCoder(err)
 			return err
 		}
@@ -203,7 +207,6 @@ func (c Command) Run(ctx *Context) (err error) {
 		c.Action = helpSubcommand.Action
 	}
 
-	context.Command = c
 	err = HandleAction(c.Action, context)
 
 	if err != nil {
@@ -250,6 +253,7 @@ func (c Command) startApp(ctx *Context) error {
 
 	// set CommandNotFound
 	app.CommandNotFound = ctx.App.CommandNotFound
+	app.CustomAppHelpTemplate = c.CustomHelpTemplate
 
 	// set the flags and commands
 	app.Commands = c.Subcommands
@@ -285,6 +289,7 @@ func (c Command) startApp(ctx *Context) error {
 	} else {
 		app.Action = helpSubcommand.Action
 	}
+	app.OnUsageError = c.OnUsageError
 
 	for index, cc := range app.Commands {
 		app.Commands[index].commandNamePath = []string{c.Name, cc.Name}

command_test.go

@@ -127,6 +127,30 @@ func TestCommand_Run_BeforeSavesMetadata(t *testing.T) {
 	}
 }
 
+func TestCommand_OnUsageError_hasCommandContext(t *testing.T) {
+	app := NewApp()
+	app.Commands = []Command{
+		{
+			Name: "bar",
+			Flags: []Flag{
+				IntFlag{Name: "flag"},
+			},
+			OnUsageError: func(c *Context, err error, _ bool) error {
+				return fmt.Errorf("intercepted in %s: %s", c.Command.Name, err.Error())
+			},
+		},
+	}
+
+	err := app.Run([]string{"foo", "bar", "--flag=wrong"})
+	if err == nil {
+		t.Fatalf("expected to receive error from Run, got none")
+	}
+
+	if !strings.HasPrefix(err.Error(), "intercepted in bar") {
+		t.Errorf("Expect an intercepted error, but got \"%v\"", err)
+	}
+}
+
 func TestCommand_OnUsageError_WithWrongFlagValue(t *testing.T) {
 	app := NewApp()
 	app.Commands = []Command{
@@ -154,6 +178,38 @@ func TestCommand_OnUsageError_WithWrongFlagValue(t *testing.T) {
 	}
 }
 
+func TestCommand_OnUsageError_WithSubcommand(t *testing.T) {
+	app := NewApp()
+	app.Commands = []Command{
+		{
+			Name: "bar",
+			Subcommands: []Command{
+				{
+					Name: "baz",
+				},
+			},
+			Flags: []Flag{
+				IntFlag{Name: "flag"},
+			},
+			OnUsageError: func(c *Context, err error, _ bool) error {
+				if !strings.HasPrefix(err.Error(), "invalid value \"wrong\"") {
+					t.Errorf("Expect an invalid value error, but got \"%v\"", err)
+				}
+				return errors.New("intercepted: " + err.Error())
+			},
+		},
+	}
+
+	err := app.Run([]string{"foo", "bar", "--flag=wrong"})
+	if err == nil {
+		t.Fatalf("expected to receive error from Run, got none")
+	}
+
+	if !strings.HasPrefix(err.Error(), "intercepted: invalid value") {
+		t.Errorf("Expect an intercepted error, but got \"%v\"", err)
+	}
+}
+
 func TestCommand_Run_SubcommandsCanUseErrWriter(t *testing.T) {
 	app := NewApp()
 	app.ErrWriter = ioutil.Discard

context.go

@@ -39,11 +39,13 @@ func (c *Context) NumFlags() int {
 
 // Set sets a context flag to a value.
 func (c *Context) Set(name, value string) error {
+	c.setFlags = nil
 	return c.flagSet.Set(name, value)
 }
 
 // GlobalSet sets a context flag to a value on the global flagset
 func (c *Context) GlobalSet(name, value string) error {
+	globalContext(c).setFlags = nil
 	return globalContext(c).flagSet.Set(name, value)
 }
 

context_test.go

@@ -375,8 +375,10 @@ func TestContext_Set(t *testing.T) {
 	set.Int("int", 5, "an int")
 	c := NewContext(nil, set, nil)
 
+	expect(t, c.IsSet("int"), false)
 	c.Set("int", "1")
 	expect(t, c.Int("int"), 1)
+	expect(t, c.IsSet("int"), true)
 }
 
 func TestContext_GlobalSet(t *testing.T) {
@@ -393,7 +395,9 @@ func TestContext_GlobalSet(t *testing.T) {
 	expect(t, c.Int("int"), 1)
 	expect(t, c.GlobalInt("int"), 5)
 
+	expect(t, c.GlobalIsSet("int"), false)
 	c.GlobalSet("int", "1")
 	expect(t, c.Int("int"), 1)
 	expect(t, c.GlobalInt("int"), 1)
+	expect(t, c.GlobalIsSet("int"), true)
 }

flag.go

@@ -14,13 +14,13 @@ import (
 const defaultPlaceholder = "value"
 
 // BashCompletionFlag enables bash-completion for all commands and subcommands
-var BashCompletionFlag = BoolFlag{
+var BashCompletionFlag Flag = BoolFlag{
 	Name:   "generate-bash-completion",
 	Hidden: true,
 }
 
 // VersionFlag prints the version for the application
-var VersionFlag = BoolFlag{
+var VersionFlag Flag = BoolFlag{
 	Name:  "version, v",
 	Usage: "print the version",
 }
@@ -28,7 +28,7 @@ var VersionFlag = BoolFlag{
 // HelpFlag prints the help for all commands and subcommands
 // Set to the zero value (BoolFlag{}) to disable flag -- keeps subcommand
 // unless HideHelp is set to true)
-var HelpFlag = BoolFlag{
+var HelpFlag Flag = BoolFlag{
 	Name:  "help, h",
 	Usage: "show help",
 }
@@ -630,7 +630,8 @@ func (f Float64Flag) ApplyWithError(set *flag.FlagSet) error {
 func visibleFlags(fl []Flag) []Flag {
 	visible := []Flag{}
 	for _, flag := range fl {
-		if !flagValue(flag).FieldByName("Hidden").Bool() {
+		field := flagValue(flag).FieldByName("Hidden")
+		if !field.IsValid() || !field.Bool() {
 			visible = append(visible, flag)
 		}
 	}
@@ -723,9 +724,8 @@ func stringifyFlag(f Flag) string {
 
 	needsPlaceholder := false
 	defaultValueString := ""
-	val := fv.FieldByName("Value")
 
-	if val.IsValid() {
+	if val := fv.FieldByName("Value"); val.IsValid() {
 		needsPlaceholder = true
 		defaultValueString = fmt.Sprintf(" (default: %v)", val.Interface())
 

help.go

@@ -47,7 +47,7 @@ var CommandHelpTemplate = `NAME:
    {{.HelpName}} - {{.Usage}}
 
 USAGE:
-   {{.HelpName}}{{if .VisibleFlags}} [command options]{{end}} {{if .ArgsUsage}}{{.ArgsUsage}}{{else}}[arguments...]{{end}}{{if .Category}}
+   {{if .UsageText}}{{.UsageText}}{{else}}{{.HelpName}}{{if .VisibleFlags}} [command options]{{end}} {{if .ArgsUsage}}{{.ArgsUsage}}{{else}}[arguments...]{{end}}{{end}}{{if .Category}}
 
 CATEGORY:
    {{.Category}}{{end}}{{if .Description}}
@@ -67,7 +67,7 @@ var SubcommandHelpTemplate = `NAME:
    {{.HelpName}} - {{if .Description}}{{.Description}}{{else}}{{.Usage}}{{end}}
 
 USAGE:
-   {{.HelpName}} command{{if .VisibleFlags}} [command options]{{end}} {{if .ArgsUsage}}{{.ArgsUsage}}{{else}}[arguments...]{{end}}
+   {{if .UsageText}}{{.UsageText}}{{else}}{{.HelpName}} command{{if .VisibleFlags}} [command options]{{end}} {{if .ArgsUsage}}{{.ArgsUsage}}{{else}}[arguments...]{{end}}{{end}}
 
 COMMANDS:{{range .VisibleCategories}}{{if .Name}}
    {{.Name}}:{{end}}{{range .VisibleCommands}}
@@ -112,17 +112,42 @@ var helpSubcommand = Command{
 // Prints help for the App or Command
 type helpPrinter func(w io.Writer, templ string, data interface{})
 
+// Prints help for the App or Command with custom template function.
+type helpPrinterCustom func(w io.Writer, templ string, data interface{}, customFunc map[string]interface{})
+
 // HelpPrinter is a function that writes the help output. If not set a default
 // is used. The function signature is:
 // func(w io.Writer, templ string, data interface{})
 var HelpPrinter helpPrinter = printHelp
 
+// HelpPrinterCustom is same as HelpPrinter but
+// takes a custom function for template function map.
+var HelpPrinterCustom helpPrinterCustom = printHelpCustom
+
 // VersionPrinter prints the version for the App
 var VersionPrinter = printVersion
 
+// ShowAppHelpAndExit - Prints the list of subcommands for the app and exits with exit code.
+func ShowAppHelpAndExit(c *Context, exitCode int) {
+	ShowAppHelp(c)
+	os.Exit(exitCode)
+}
+
 // ShowAppHelp is an action that displays the help.
-func ShowAppHelp(c *Context) error {
+func ShowAppHelp(c *Context) (err error) {
+	if c.App.CustomAppHelpTemplate == "" {
 		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
 }
 
@@ -138,6 +163,12 @@ func DefaultAppComplete(c *Context) {
 	}
 }
 
+// ShowCommandHelpAndExit - exits with code after showing help
+func ShowCommandHelpAndExit(c *Context, command string, code int) {
+	ShowCommandHelp(c, command)
+	os.Exit(code)
+}
+
 // ShowCommandHelp prints help for the given command
 func ShowCommandHelp(ctx *Context, command string) error {
 	// show the subcommand help for a command with subcommands
@@ -148,7 +179,11 @@ func ShowCommandHelp(ctx *Context, command string) error {
 
 	for _, c := range ctx.App.Commands {
 		if c.HasName(command) {
+			if c.CustomHelpTemplate != "" {
+				HelpPrinterCustom(ctx.App.Writer, c.CustomHelpTemplate, c, nil)
+			} else {
 				HelpPrinter(ctx.App.Writer, CommandHelpTemplate, c)
+			}
 			return nil
 		}
 	}
@@ -191,10 +226,15 @@ func ShowCommandCompletions(ctx *Context, command string) {
 	}
 }
 
-func printHelp(out io.Writer, templ string, data interface{}) {
+func printHelpCustom(out io.Writer, templ string, data interface{}, customFunc map[string]interface{}) {
 	funcMap := template.FuncMap{
 		"join": strings.Join,
 	}
+	if customFunc != nil {
+		for key, value := range customFunc {
+			funcMap[key] = value
+		}
+	}
 
 	w := tabwriter.NewWriter(out, 1, 8, 2, ' ', 0)
 	t := template.Must(template.New("help").Funcs(funcMap).Parse(templ))
@@ -210,10 +250,14 @@ func printHelp(out io.Writer, templ string, data interface{}) {
 	w.Flush()
 }
 
+func printHelp(out io.Writer, templ string, data interface{}) {
+	printHelpCustom(out, templ, data, nil)
+}
+
 func checkVersion(c *Context) bool {
 	found := false
-	if VersionFlag.Name != "" {
+	if VersionFlag.GetName() != "" {
-		eachName(VersionFlag.Name, func(name string) {
+		eachName(VersionFlag.GetName(), func(name string) {
 			if c.GlobalBool(name) || c.Bool(name) {
 				found = true
 			}
@@ -224,8 +268,8 @@ func checkVersion(c *Context) bool {
 
 func checkHelp(c *Context) bool {
 	found := false
-	if HelpFlag.Name != "" {
+	if HelpFlag.GetName() != "" {
-		eachName(HelpFlag.Name, func(name string) {
+		eachName(HelpFlag.GetName(), func(name string) {
 			if c.GlobalBool(name) || c.Bool(name) {
 				found = true
 			}
@@ -260,7 +304,7 @@ func checkShellCompleteFlag(a *App, arguments []string) (bool, []string) {
 	pos := len(arguments) - 1
 	lastArg := arguments[pos]
 
-	if lastArg != "--"+BashCompletionFlag.Name {
+	if lastArg != "--"+BashCompletionFlag.GetName() {
 		return false, arguments
 	}
 

help_test.go

@@ -3,6 +3,8 @@ package cli
 import (
 	"bytes"
 	"flag"
+	"fmt"
+	"runtime"
 	"strings"
 	"testing"
 )
@@ -256,6 +258,92 @@ 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 TestShowSubcommandHelp_CommandUsageText(t *testing.T) {
+	app := &App{
+		Commands: []Command{
+			{
+				Name:      "frobbly",
+				UsageText: "this is usage text",
+			},
+		},
+	}
+
+	output := &bytes.Buffer{}
+	app.Writer = output
+
+	app.Run([]string{"foo", "frobbly", "--help"})
+
+	if !strings.Contains(output.String(), "this is usage text") {
+		t.Errorf("expected output to include usage text; got: %q", output.String())
+	}
+}
+
+func TestShowSubcommandHelp_SubcommandUsageText(t *testing.T) {
+	app := &App{
+		Commands: []Command{
+			{
+				Name: "frobbly",
+				Subcommands: []Command{
+					{
+						Name:      "bobbly",
+						UsageText: "this is usage text",
+					},
+				},
+			},
+		},
+	}
+
+	output := &bytes.Buffer{}
+	app.Writer = output
+	app.Run([]string{"foo", "frobbly", "bobbly", "--help"})
+
+	if !strings.Contains(output.String(), "this is usage text") {
+		t.Errorf("expected output to include usage text; got: %q", output.String())
+	}
+}
+
 func TestShowAppHelp_HiddenCommand(t *testing.T) {
 	app := &App{
 		Commands: []Command{
@@ -287,3 +375,78 @@ 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())
+	}
+}