checker: split monolithic rule into per-concern rules

checker/rules_syntax.go

@@ -0,0 +1,13 @@
+package checker
+
+import sdk "git.happydns.org/checker-sdk-go/checker"
+
+// syntaxRule covers Zonemaster's syntax test module (domain name syntax,
+// hostname legality).
+func syntaxRule() sdk.CheckRule {
+	return &categoryRule{
+		name:        "zonemaster.syntax",
+		description: "Zonemaster syntax tests (domain name syntax, hostname legality).",
+		modules:     []string{"syntax"},
+	}
+}