Updates from reviewers

cmd/fakes/main.go

@@ -10,10 +10,12 @@
 package main
 
 import (
+	"errors"
 	"flag"
 	"fmt"
 	"io"
 	"os"
+	"runtime/debug"
 	"strings"
 
 	"github.com/Timewave-AB/fakes"
@@ -25,7 +27,11 @@ const usage = `Usage: fakes -data-path D [-data-path D]... [-seed N] [-repeat N]
   <path>        a category, or a dotted path into one (person, person.last)
   -seed N       seed for reproducible output
   -repeat N     render the path N times (default 1)
-  -separator S  string between repeated values (default newline)`
+  -separator S  string between repeated values (default newline)
+  -list         list the paths the data offers, then exit
+  -version      print the version, then exit
+
+Flags must come before <path>.`
 
 // stringList collects a repeatable string flag, preserving order.
 type stringList []string
@@ -45,19 +51,24 @@ func run(args []string, stdout, stderr io.Writer) int {
 	seed := fs.Uint64("seed", 0, "seed for reproducible output")
 	repeat := fs.Int("repeat", 1, "render the path this many times")
 	sep := fs.String("separator", "\n", "string between repeated values")
+	list := fs.Bool("list", false, "list the paths the data offers, then exit")
+	showVersion := fs.Bool("version", false, "print the version, then exit")
 	var dirs stringList
 	fs.Var(&dirs, "data-path", "a data directory to load (repeatable)")
 	if err := fs.Parse(args); err != nil {
+		if errors.Is(err, flag.ErrHelp) { // -h/-help already printed usage
+			return 0
+		}
 		return 2
 	}
-	if len(dirs) == 0 || fs.NArg() != 1 {
+	if *showVersion {
+		fmt.Fprintln(stdout, "fakes "+buildVersion())
+		return 0
+	}
+	if len(dirs) == 0 {
 		fs.Usage()
 		return 2
 	}
-	if *repeat < 1 {
-		fmt.Fprintln(stderr, "repeat must be a positive integer")
-		return 2
-	}
 
 	var opts []fakes.Option
 	fs.Visit(func(fl *flag.Flag) {
@@ -66,6 +77,26 @@ func run(args []string, stdout, stderr io.Writer) int {
 		}
 	})
 
+	if *list {
+		f, err := fakes.New(dirs, opts...)
+		if err != nil {
+			fmt.Fprintln(stderr, err)
+			return 1
+		}
+		for _, p := range f.List() {
+			fmt.Fprintln(stdout, p)
+		}
+		return 0
+	}
+	if fs.NArg() != 1 {
+		fs.Usage()
+		return 2
+	}
+	if *repeat < 1 {
+		fmt.Fprintln(stderr, "repeat must be a positive integer")
+		return 2
+	}
+
 	path := fs.Arg(0)
 	f, err := fakes.New(dirs, opts...)
 	if err != nil {
@@ -82,3 +113,13 @@ func run(args []string, stdout, stderr io.Writer) int {
 	fmt.Fprintln(stdout, strings.Join(vals, *sep))
 	return 0
 }
+
+// buildVersion reports the module version stamped into the binary by `go install`
+// (or "devel" for a local build), read from the build info — no version constant
+// to bump, no extra dependency.
+func buildVersion() string {
+	if info, ok := debug.ReadBuildInfo(); ok && info.Main.Version != "" {
+		return info.Main.Version
+	}
+	return "devel"
+}