AlbertMoscow · October 26, 2019 05:21 · Jul 17, 2013 · Jul 17, 2013
diff --git a/roman_numerals.exs b/roman_numerals.exs
@@ -1,32 +1,24 @@
 defmodule RomanNumerals do
 
-    @moduledoc """
+	@moduledoc """
 	Task definition: Create a function taking a positive integer as its parameter and
 	returning a string containing the Roman Numeral representation of that integer.
 	"""
 
-	def convert 0 do
-            ''
-  	end
-
-  	def convert(number) when number >= 10 do
-            'X' ++ convert(number - 10)
-  	end
+  	def convert(number) do
+	    convert(number, [[10,'X'], [9,'IX'], [5,'V'], [4,'IV'], [1,'I']])
+  	end  	
 
-  	def convert(number) when number >= 9 do
-            'IX' ++ convert(number - 9)
+  	defp convert(0, _) do
+	     ''
   	end
 
-  	def convert(number) when number >= 5 do
-            'V' ++ convert(number - 5)
+  	defp convert(number, [[arabic, roman]|_] = l) when number >= arabic do
+	     roman ++ convert(number - arabic, l)
   	end
 
-  	def convert(number) when number >= 4 do
-            'IV' ++ convert(number - 4)
-  	end
-
-  	def convert(number) when number >= 1 do
-            'I' ++ convert(number - 1)
+  	defp convert(number, [_|t]) do
+	     convert(number, t)
   	end
 end
 

diff --git a/roman_numerals.exs b/roman_numerals.exs
@@ -0,0 +1,58 @@
+defmodule RomanNumerals do
+
+    @moduledoc """
+	Task definition: Create a function taking a positive integer as its parameter and
+	returning a string containing the Roman Numeral representation of that integer.
+	"""
+
+	def convert 0 do
+            ''
+  	end
+
+  	def convert(number) when number >= 10 do
+            'X' ++ convert(number - 10)
+  	end
+
+  	def convert(number) when number >= 9 do
+            'IX' ++ convert(number - 9)
+  	end
+
+  	def convert(number) when number >= 5 do
+            'V' ++ convert(number - 5)
+  	end
+
+  	def convert(number) when number >= 4 do
+            'IV' ++ convert(number - 4)
+  	end
+
+  	def convert(number) when number >= 1 do
+            'I' ++ convert(number - 1)
+  	end
+end
+
+ExUnit.start
+
+defmodule RomanNumeralsTest do
+  use ExUnit.Case
+
+  test "converts arabic numbers to roman" do
+  	Enum.each [ [1,'I'],
+  		    [2,'II'],
+		    [3,'III'],
+  		    [4,'IV'],
+  		    [5,'V'],
+  		    [6,'VI'],
+  		    [7,'VII'],
+  		    [8,'VIII'],
+  		    [9,'IX'],
+  		    [10,'X'],
+  		    [11,'XI'],
+  		    [14,'XIV'],
+  		    [19,'XIX'],
+  		    [20,'XX'],
+  		    [25,'XXV'],
+  		    [27,'XXVII'] ], fn [arabic, roman] ->
+  		assert roman == RomanNumerals.convert(arabic)
+  	end
+  end
+end