More tests and write usage to stdout

internal/cli/app.go

@@ -43,6 +43,7 @@ func printAppVersion() {
 
 func (a *App) Run(args ...string) error {
 	fset := flag.NewFlagSet("pocryp", flag.ExitOnError)
+	fset.SetOutput(os.Stdout)
 	fset.Usage = a.Usage
 	fset.BoolVar(&a.printVersion, "version", false, "")
 	if err := fset.Parse(args); err != nil {
@@ -122,8 +123,7 @@ func (a App) maxCommandName(category string) int {
 }
 
 func (a App) Usage() {
-	w := os.Stderr
-	fmt.Fprint(w, `Usage: pocryp command [ARGS]
+	fmt.Print(`Usage: pocryp command [ARGS]
 
 Flags:
   -h, --help  Print this message
@@ -133,13 +133,13 @@ Commands(by category):
 
 `)
 	for _, v := range a.categories {
-		fmt.Fprintf(w, "%s:\n", v.name)
+		fmt.Printf("%s:\n", v.name)
 		mlen := a.maxCommandName(v.name)
 		for _, cmd := range v.commands {
 			padding := strings.Repeat(" ", mlen-len(cmd.Name))
-			fmt.Fprintf(w, "  %s%s  %s\n", cmd.Name, padding, cmd.Brief)
+			fmt.Printf("  %s%s  %s\n", cmd.Name, padding, cmd.Brief)
 		}
-		fmt.Fprint(w, "\n")
+		fmt.Print("\n")
 	}
-	fmt.Fprint(w, "Run 'pocryp command -h' for more information about a command.\n")
+	fmt.Print("Run 'pocryp command -h' for more information about a command.\n")
 }

internal/cli/cmd/command.go

@@ -34,10 +34,11 @@ func (c *Command) Init() {
 		panic("cmd: missing Brief")
 	}
 	c.Flags = flag.NewFlagSet(c.Name, flag.ContinueOnError)
+	c.Flags.SetOutput(os.Stdout)
 	c.Flags.Usage = func() {
-		fmt.Fprint(os.Stderr, c.Usage)
-		fmt.Fprintln(os.Stderr, "Options:")
+		fmt.Print(c.Usage)
+		fmt.Println("Options:")
 		c.Flags.PrintDefaults()
-		fmt.Fprint(os.Stderr, "\n")
+		fmt.Print("\n")
 	}
 }

internal/cli/cmd/command_test.go

@@ -0,0 +1,100 @@
+package cmd
+
+import (
+	"testing"
+)
+
+func TestParse(t *testing.T) {
+	c := Command{
+		Run:   func(*Command) error { return nil },
+		Name:  "foo",
+		Usage: "bar",
+		Brief: "baz",
+	}
+
+	c.Init()
+
+	t.Run("Err", func(t *testing.T) {
+		c.Args = []string{"-foo"}
+		if err := c.Parse(); err == nil {
+			t.Fatal("expected error")
+		}
+	})
+
+	t.Run("Ok", func(t *testing.T) {
+		c.Args = []string{"foo", "bar"}
+		if err := c.Parse(); err != nil {
+			t.Fatal(err)
+		}
+	})
+}
+
+func TestInit(t *testing.T) {
+	tests := []struct {
+		name string
+		msg  string
+		cmd  Command
+	}{
+		{
+			name: "NoRun",
+			msg:  "cmd: missing Run",
+			cmd:  Command{},
+		},
+
+		{
+			name: "NoName",
+			msg:  "cmd: missing Name",
+			cmd: Command{
+				Run: func(*Command) error { return nil },
+			},
+		},
+
+		{
+			name: "NoUsage",
+			msg:  "cmd: missing Usage",
+			cmd: Command{
+				Run:  func(*Command) error { return nil },
+				Name: "foo",
+			},
+		},
+
+		{
+			name: "NoBrief",
+			msg:  "cmd: missing Brief",
+			cmd: Command{
+				Run:   func(*Command) error { return nil },
+				Name:  "foo",
+				Usage: "bar",
+			},
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			defer expectPanic(t, test.msg)
+			test.cmd.Init()
+		})
+	}
+
+	t.Run("Ok", func(t *testing.T) {
+		c := Command{
+			Run:   func(*Command) error { return nil },
+			Name:  "foo",
+			Usage: "bar",
+			Brief: "baz",
+		}
+		c.Init()
+		c.Flags.Usage()
+	})
+}
+
+func expectPanic(t *testing.T, msg string) {
+	t.Helper()
+	r := recover()
+	if r == nil {
+		t.Fatal("expected panic")
+	}
+	if r != msg {
+		t.Fatalf("want %q, have %q", msg, r)
+	}
+}