Tests: no hint where a reference would mean something else, and every reference the help advertises resolves

cmd/fejkdata/main_test.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"os"
 	"path/filepath"
+	"regexp"
 	"strings"
 	"testing"
 )
@@ -333,6 +334,15 @@ func TestClassify(t *testing.T) {
 	}
 }
 
+func TestUsageReferencesResolve(t *testing.T) {
+	for _, token := range regexp.MustCompile(`\{/[^}]+\}`).FindAllString(usage, -1) {
+		code, out, errb := runOut("--seed", "1", token)
+		if code != 0 || strings.TrimSpace(out) == "" {
+			t.Errorf("usage advertises %s: run = %d, %q, stderr %q", token, code, out, errb)
+		}
+	}
+}
+
 func TestRunShapeMisuseBeforeLoad(t *testing.T) {
 	code, _, errb := runOut("--no-shipped-data", "[abc]")
 	if code != 2 || !strings.Contains(errb, "[abc]") || strings.Contains(errb, "--data-path") {