diff --git a/main.go b/main.go
index 24a9ba4..b79135e 100644
--- a/main.go
+++ b/main.go
@@ -18,6 +18,8 @@ type Fields struct {
 	Episode string
 }
 
+type MvNLn func(string, string) error
+
 func main() {
 	ctx, can := signal.NotifyContext(context.Background(), syscall.SIGINT)
 	defer can()
@@ -30,12 +32,13 @@ func main() {
 		os.Args[2],
 		os.Args[4:],
 		overrides,
+		RealMvNLn,
 	); err != nil {
 		panic(err)
 	}
 }
 
-func Run(ctx context.Context, outd, ind string, patterns []string, overrides Fields) error {
+func Run(ctx context.Context, outd, ind string, patterns []string, overrides Fields, mvNLn MvNLn) error {
 	entries, err := os.ReadDir(ind)
 	if err != nil {
 		return err
@@ -44,14 +47,14 @@ func Run(ctx context.Context, outd, ind string, patterns []string, overrides Fie
 		if !entry.Type().IsRegular() {
 			continue
 		}
-		if err := one(ctx, outd, path.Join(ind, entry.Name()), patterns, overrides); err != nil {
+		if err := one(ctx, outd, path.Join(ind, entry.Name()), patterns, overrides, mvNLn); err != nil {
 			return err
 		}
 	}
 	return nil
 }
 
-func one(ctx context.Context, outd, inf string, patterns []string, overrides Fields) error {
+func one(ctx context.Context, outd, inf string, patterns []string, overrides Fields, mvNLn MvNLn) error {
 	f := path.Base(inf)
 	for _, pattern := range patterns {
 		re := regexp.MustCompile(pattern)
@@ -81,13 +84,17 @@ func one(ctx context.Context, outd, inf string, patterns []string, overrides Fie
 		}
 		found.Title = strings.Join(strings.Fields(found.Title), "_")
 
-		return mvNLn(ctx, outd, inf, found)
+		return foundOne(ctx, outd, inf, found, mvNLn)
 	}
 	return nil
 }
 
-func mvNLn(ctx context.Context, outd, inf string, fields Fields) error {
+func foundOne(ctx context.Context, outd, inf string, fields Fields, mvNLn MvNLn) error {
 	outf := path.Join(outd, fmt.Sprintf("%s_S%sE%s%s", fields.Title, fields.Season, fields.Episode, path.Ext(inf)))
+	return mvNLn(outf, inf)
+}
+
+func RealMvNLn(outf, inf string) error {
 	if _, err := os.Stat(outf); err == nil {
 		return nil // fmt.Errorf("conflict: %s already exists", path.Base(outf))
 	}
diff --git a/main_test.go b/main_test.go
index c56c341..c860e3b 100644
--- a/main_test.go
+++ b/main_test.go
@@ -64,9 +64,9 @@ func TestRun(t *testing.T) {
 			}
 			outd := t.TempDir()
 
-			if err := main.Run(context.Background(), outd, ind, c.patterns, c.overrides); err != nil {
+			if err := main.Run(context.Background(), outd, ind, c.patterns, c.overrides, main.RealMvNLn); err != nil {
 				t.Fatal("err on first run:", err)
-			} else if err := main.Run(context.Background(), outd, ind, c.patterns, c.overrides); err != nil {
+			} else if err := main.Run(context.Background(), outd, ind, c.patterns, c.overrides, main.RealMvNLn); err != nil {
 				t.Fatal("err on second run:", err)
 			}