Fix Denmark to ignore a - 🇩🇰

CHANGELOG.md

@@ -1,5 +1,8 @@
 ## [Unreleased]
 
+Fixes:
+- Fix Denmark to ignore a `-` 🇩🇰
+
 ## [1.3.1] - 2026-03-24
 
 Fixes:

lib/tin_valid/denmark_tin.rb

@@ -15,7 +15,7 @@ def initialize(tin:, birth_date: nil)
     def valid?
       match = MATCHER.match(tin)
       return false unless match
-      return false if tin == "0000000000"
+      return false if normalized_tin == "0000000000"
 
       if birth_date
         year = "#{birth_century}#{match[:year]}"
@@ -35,6 +35,7 @@ def valid?
       (?<day>[0-3][0-9])
       (?<month>[0-1][0-9])
       (?<year>[0-9]{2})
+      -?
       (?<serial>
         [0-9]{3}
         (?<check>[0-9])
@@ -43,6 +44,8 @@ def valid?
     }x
     private_constant :MATCHER
 
+    def normalized_tin = @normalized_tin ||= tin.sub("-", "")
+
     def birth_century = birth_date.strftime("%Y")[..1]
     def birth_year = birth_date.year
 
@@ -51,7 +54,7 @@ def checksum
       weights =
         [4, 3, 2, 7, 6, 5, 4, 3, 2]
           .each_with_index
-          .map { |char, index| char.to_i * tin[index].to_i }
+          .map { |char, index| char.to_i * normalized_tin[index].to_i }
 
       # 2. Add up the results of the above multiplications;
       sum = weights.sum

spec/tin_valid/denmark_tin_spec.rb

@@ -4,6 +4,7 @@
   describe "#valid?" do
     valid_values = [
       ["0101111113", nil],
+      ["010111-1113", nil],
       ["0101111113", Date.new(1911, 1, 1)],
       ["2808784028", nil],
       ["2808784028", Date.new(1978, 8, 28)],