stembuild: messenger for HelpCommand

Author: aramprice

stembuild/commandparser/help.go

@@ -3,13 +3,13 @@ package commandparser
 import (
 	"context"
 	"flag"
-	"fmt"
 	"io"
 	"os"
 	"path"
 
 	"github.com/google/subcommands"
 
+	"github.com/cloudfoundry/bosh-windows-stemcell-builder/stembuild/messenger"
 	"github.com/cloudfoundry/bosh-windows-stemcell-builder/stembuild/version"
 )
 
@@ -50,37 +50,29 @@ func (h *stembuildHelp) Usage() string {
 	return h.commander.HelpCommand().Usage()
 }
 
-func (h *stembuildHelp) Execute(c context.Context, f *flag.FlagSet, args ...interface{}) subcommands.ExitStatus {
-	switch f.NArg() {
+func (h *stembuildHelp) Execute(ctx context.Context, flagSet *flag.FlagSet, args ...interface{}) subcommands.ExitStatus {
+	switch flagSet.NArg() {
 	case 0:
 		h.Explain(h.commander.Output)
 		return subcommands.ExitSuccess
 
 	default:
-		return h.commander.HelpCommand().Execute(c, f, args)
+		return h.commander.HelpCommand().Execute(ctx, flagSet, args)
 	}
 }
 
-func (h *stembuildHelp) Explain(w io.Writer) {
+func (h *stembuildHelp) Explain(output io.Writer) {
+	helpMessenger := messenger.NewHelpMessenger(output)
 
-	fmt.Fprintf(w, "%s version %s, Windows Stemcell Building Tool\n\n", path.Base(os.Args[0]), version.Current) //nolint:errcheck
-	fmt.Fprintf(w, "Usage: %s <global options> <command> <command flags>\n\n", path.Base(os.Args[0]))           //nolint:errcheck
+	helpMessenger.UsagePreamble(path.Base(os.Args[0]), version.Current)
 
-	fmt.Fprint(w, "Commands:\n") //nolint:errcheck
+	helpMessenger.PrintCommandPreamble()
 	for _, command := range *h.commands {
-		if len(command.Name()) < 5 { // This help align the synopses when the commands are of different lengths
-			fmt.Fprintf(w, "  %s\t\t%s\n", command.Name(), command.Synopsis()) //nolint:errcheck
-		} else {
-			fmt.Fprintf(w, "  %s\t%s\n", command.Name(), command.Synopsis()) //nolint:errcheck
-		}
+		helpMessenger.PrintCommand(command.Name(), command.Synopsis())
 	}
 
-	fmt.Fprint(w, "\nGlobal Options:\n") //nolint:errcheck
+	helpMessenger.PrintGlobalFlagPreamble()
 	h.topLevelFlags.VisitAll(func(f *flag.Flag) {
-		if len(f.Name) > 1 {
-			fmt.Fprintf(w, "  -%s\t%s\n", f.Name, f.Usage) //nolint:errcheck
-		} else {
-			fmt.Fprintf(w, "  -%s\t\t%s\n", f.Name, f.Usage) //nolint:errcheck
-		}
+		helpMessenger.PrintGlobalFlag(f.Name, f.Usage)
 	})
 }

stembuild/messenger/help_messenger.go

@@ -0,0 +1,43 @@
+package messenger
+
+import (
+	"fmt"
+	"io"
+)
+
+func NewHelpMessenger(output io.Writer) *HelpMessenger {
+	return &HelpMessenger{output: output}
+}
+
+type HelpMessenger struct {
+	output io.Writer
+}
+
+func (m *HelpMessenger) UsagePreamble(executable string, version string) {
+	write(m.output, fmt.Sprintf("%s version %s, Windows Stemcell Building Tool\n\n", executable, version))
+	write(m.output, fmt.Sprintf("Usage: %s <global options> <command> <command flags>\n\n", executable))
+}
+
+func (m *HelpMessenger) PrintCommandPreamble() {
+	write(m.output, "Commands:\n")
+}
+
+func (m *HelpMessenger) PrintCommand(command string, description string) {
+	if len(command) < 5 { // This help align the synopses when the commands are of different lengths
+		write(m.output, fmt.Sprintf("  %s\t\t%s\n", command, description))
+	} else {
+		write(m.output, fmt.Sprintf("  %s\t%s\n", command, description))
+	}
+}
+
+func (m *HelpMessenger) PrintGlobalFlagPreamble() {
+	write(m.output, "\nGlobal Options:\n")
+}
+
+func (m *HelpMessenger) PrintGlobalFlag(flag string, usage string) {
+	if len(flag) > 1 {
+		write(m.output, fmt.Sprintf("  -%s\t%s\n", flag, usage))
+	} else {
+		write(m.output, fmt.Sprintf("  -%s\t\t%s\n", flag, usage))
+	}
+}

stembuild/messenger/help_messenger_test.go

@@ -0,0 +1,115 @@
+package messenger_test
+
+import (
+	"fmt"
+
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+	. "github.com/onsi/gomega/gbytes"
+
+	"github.com/cloudfoundry/bosh-windows-stemcell-builder/stembuild/messenger"
+)
+
+var _ = Describe("HelpMessenger", func() {
+	var (
+		buf *Buffer
+		m   *messenger.HelpMessenger
+	)
+
+	BeforeEach(func() {
+		buf = NewBuffer()
+		m = messenger.NewHelpMessenger(buf)
+	})
+
+	Describe("UsagePreamble", func() {
+		It("outputs the expected text", func() {
+			executable := "STEMBUILD_EXECUTABLE"
+			version := "STEMBUILD_VERSION"
+			m.UsagePreamble(executable, version)
+
+			expectedText :=
+				fmt.Sprintf("%s version %s, Windows Stemcell Building Tool\n\n", executable, version) +
+					fmt.Sprintf("Usage: %s <global options> <command> <command flags>\n\n", executable)
+
+			Eventually(buf).Should(Say(expectedText))
+		})
+	})
+
+	Describe("PrintCommandPreamble", func() {
+		It("outputs the expected text", func() {
+			m.PrintCommandPreamble()
+
+			Eventually(buf).Should(Say("Commands:\n"))
+		})
+	})
+
+	Describe("PrintCommand", func() {
+		var (
+			command     string
+			description = "COMMAND DESCRIPTION"
+		)
+
+		Context("when the command name is shorter than 5 characters", func() {
+			BeforeEach(func() {
+				command = "CMD"
+			})
+
+			It("outputs the expected text", func() {
+				m.PrintCommand(command, description)
+
+				Eventually(buf).Should(Say(fmt.Sprintf("  %s\t\t%s\n", command, description)))
+			})
+		})
+
+		Context("when the command name is longer than 5 characters", func() {
+			BeforeEach(func() {
+				command = "LONG_CMD"
+			})
+
+			It("outputs the expected text", func() {
+				m.PrintCommand(command, description)
+
+				Eventually(buf).Should(Say(fmt.Sprintf("  %s\t%s\n", command, description)))
+			})
+		})
+	})
+
+	Describe("PrintGlobalFlagPreamble", func() {
+		It("outputs the expected text", func() {
+			m.PrintGlobalFlagPreamble()
+
+			Eventually(buf).Should(Say("\nGlobal Options:\n"))
+		})
+	})
+
+	Describe("PrintGlobalFlag", func() {
+		var (
+			flag  string
+			usage = "FLAG USAGE"
+		)
+
+		Context("when the flag is longer than 1 character", func() {
+			BeforeEach(func() {
+				flag = "long-flag"
+			})
+
+			It("outputs the expected text", func() {
+				m.PrintGlobalFlag(flag, usage)
+
+				Eventually(buf).Should(Say(fmt.Sprintf("  -%s\t%s\n", flag, usage)))
+			})
+		})
+
+		Context("when the flag is shorter than 1 character", func() {
+			BeforeEach(func() {
+				flag = "f"
+			})
+
+			It("outputs the expected text", func() {
+				m.PrintGlobalFlag(flag, usage)
+
+				Eventually(buf).Should(Say(fmt.Sprintf("  -%s\t\t%s\n", flag, usage)))
+			})
+		})
+	})
+})