Add CLI -repeat and -separator flags for emitting multiple values

cmd/fakes/main.go

@@ -14,15 +14,18 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"strings"
 
 	"github.com/Timewave-AB/fakes"
 )
 
-const usage = `Usage: fakes [-seed N] <data-dir>... <path>
+const usage = `Usage: fakes [-seed N] [-repeat N] [-separator S] <data-dir>... <path>
 
-  <data-dir>  one or more data directories, e.g. ./data/sv_SE (last wins on clash)
-  <path>      a category, or a dotted path into one (person, person.last)
-  -seed N     seed for reproducible output`
+  <data-dir>    one or more data directories, e.g. ./data/sv_SE (last wins on clash)
+  <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)`
 
 func main() { os.Exit(run(os.Args[1:], os.Stdout, os.Stderr)) }
 
@@ -33,6 +36,8 @@ func run(args []string, stdout, stderr io.Writer) int {
 	fs.SetOutput(stderr)
 	fs.Usage = func() { fmt.Fprintln(stderr, usage) }
 	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")
 	if err := fs.Parse(args); err != nil {
 		return 2
 	}
@@ -40,6 +45,10 @@ func run(args []string, stdout, stderr io.Writer) int {
 		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) {
@@ -54,11 +63,13 @@ func run(args []string, stdout, stderr io.Writer) int {
 		fmt.Fprintln(stderr, err)
 		return 1
 	}
-	v, err := f.Fake(path)
-	if err != nil {
-		fmt.Fprintln(stderr, err)
-		return 1
+	vals := make([]string, *repeat)
+	for i := range vals {
+		if vals[i], err = f.Fake(path); err != nil {
+			fmt.Fprintln(stderr, err)
+			return 1
+		}
 	}
-	fmt.Fprintln(stdout, v)
+	fmt.Fprintln(stdout, strings.Join(vals, *sep))
 	return 0
 }

cmd/fakes/main_test.go

@@ -57,6 +57,60 @@ func TestRunSeedDeterministic(t *testing.T) {
 	}
 }
 
+func TestRunRepeat(t *testing.T) {
+	// -repeat N prints N values, one per line by default.
+	code, out, errb := runOut("-seed", "1", "-repeat", "3", svSE, "word")
+	if code != 0 {
+		t.Fatalf("run = %d, stderr=%q", code, errb)
+	}
+	lines := strings.Split(strings.TrimRight(out, "\n"), "\n")
+	if len(lines) != 3 {
+		t.Errorf("repeat=3 gave %d lines: %q", len(lines), out)
+	}
+}
+
+func TestRunSeparator(t *testing.T) {
+	// -separator joins the repeated values instead of newlines.
+	code, out, errb := runOut("-repeat", "3", "-separator", ",", svSE, "word")
+	if code != 0 {
+		t.Fatalf("run = %d, stderr=%q", code, errb)
+	}
+	if n := strings.Count(out, "\n"); n != 1 {
+		t.Errorf("want one trailing newline, got %d: %q", n, out)
+	}
+	if !strings.Contains(out, ",") {
+		t.Errorf("values should be comma-joined: %q", out)
+	}
+}
+
+func TestRunRepeatAdvancesRNG(t *testing.T) {
+	// Each repeat is a fresh draw, not the same value N times.
+	code, out, errb := runOut("-seed", "1", "-repeat", "5", svSE, "person")
+	if code != 0 {
+		t.Fatalf("run = %d, stderr=%q", code, errb)
+	}
+	uniq := map[string]bool{}
+	for _, l := range strings.Split(strings.TrimRight(out, "\n"), "\n") {
+		uniq[l] = true
+	}
+	if len(uniq) < 2 {
+		t.Errorf("repeat should vary output, all identical: %q", out)
+	}
+}
+
+func TestRunRepeatInvalid(t *testing.T) {
+	// A non-positive repeat is misuse.
+	for _, r := range []string{"0", "-1"} {
+		code, _, errb := runOut("-repeat", r, svSE, "word")
+		if code != 2 {
+			t.Errorf("repeat=%s = %d, want 2", r, code)
+		}
+		if errb == "" {
+			t.Errorf("repeat=%s: want an error message", r)
+		}
+	}
+}
+
 func TestRunUsageOnTooFewArgs(t *testing.T) {
 	// Need at least one data dir plus a path; fewer is misuse.
 	for _, args := range [][]string{{}, {svSE}} {