Add method Repubmark.validate_slug!

lib/repubmark.rb

@@ -66,6 +66,8 @@ require_relative 'repubmark/elems/footnote'
 module Repubmark
   FORMATS = %i[gemtext html summary_plain word_count].freeze
 
+  SLUG_RE = /\A\w+(-\w+)*\z/
+
   UNICODE_SUPS = {
     '0' => '⁰',
     '1' => '¹',
@@ -102,6 +104,13 @@ module Repubmark
     ')' => '₎',
   }.freeze
 
+  def self.validate_slug!(slug)
+    slug = String(slug).freeze
+    raise 'Invalid slug' unless SLUG_RE.match? slug
+
+    slug
+  end
+
   def self.unicode_sup(val)
     String(val).each_char.map { |chr| UNICODE_SUPS.fetch chr }.join.freeze
   end