Add catalog-zone-gen tool

Generate RFC 9432 DNS catalog zone files from a declarative input file.
Parses zone-to-catalog assignments with optional group and coo properties,
produces deterministic BIND-format output with automatic SOA serial
management and change detection.

helpers_test.go

@@ -0,0 +1,30 @@
+package main
+
+import (
+	"strings"
+	"testing"
+	"time"
+)
+
+func fixedTime(year, month, day int) time.Time {
+	return time.Date(year, time.Month(month), day, 0, 0, 0, 0, time.UTC)
+}
+
+func splitLines(s string) []string {
+	s = strings.TrimRight(s, "\n")
+	if s == "" {
+		return nil
+	}
+	return strings.Split(s, "\n")
+}
+
+func assertContains(t *testing.T, s, substr string) {
+	t.Helper()
+	if !strings.Contains(s, substr) {
+		t.Errorf("expected %q to contain %q", s, substr)
+	}
+}
+
+func containsStr(s, substr string) bool {
+	return strings.Contains(s, substr)
+}