Fix Denmark check for certain ranges of birth years 🇩🇰

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 Fixes:
 - Fix Finland checks for tins ending in `P` 🇫🇮
+- Fix Denmark check for certain ranges of birth years 🇩🇰
 
 ## [1.2.1] - 2025-05-22
 

lib/tin_valid/denmark_tin.rb

@@ -72,14 +72,15 @@ def checksum
     # rubocop:disable Metrics/PerceivedComplexity
     def check_serial(serial, year)
       case serial.to_i
-      in 1..3999
+      when 1..3999
         (1900..1999).cover?(birth_year)
-      in 4000..4999, 9000..9999
+      when 4000..4999,
+           9000..9999
         case year.to_i
         in 0..36 then (2000..2036).cover?(birth_year)
         in 36..99 then (1937..1999).cover?(birth_year)
         end
-      in 5000..8999
+      when 5000..8999
         case year.to_i
         in 0..36 then (2000..2036).cover?(birth_year)
         in 37..57 then false

spec/tin_valid/denmark_tin_spec.rb

@@ -5,6 +5,8 @@
     valid_values = [
       ["0101111113", nil],
       ["0101111113", Date.new(1911, 1, 1)],
+      ["2808784028", nil],
+      ["2808784028", Date.new(1978, 8, 28)],
     ]
 
     invalid_values = [