finished recursive method ^_^

hamming_recursive.rb

@@ -0,0 +1,24 @@
+class Hamming
+
+  def self.compute(strand1, strand2, hamming_distance = 0)
+
+    strand1_array = strand1.split(//)
+    strand2_array = strand2.split(//)
+
+    if strand1_array.length != strand2_array.length
+      raise ArgumentError, "Strands must be the same length."
+    end
+
+    return hamming_distance if strand1_array.empty? && strand2_array.empty?
+
+    hamming_distance += 1 if strand1_array[0] != strand2_array[0]
+
+    strand1_array.shift
+    strand2_array.shift
+
+    return self.compute(strand1_array.join, strand2_array.join, hamming_distance)
+
+
+  end
+
+end

hamming_test.rb

@@ -1,75 +1,61 @@
 gem 'minitest', '>= 5.0.0'
 require 'minitest/autorun'
-require_relative 'hamming'
+require_relative 'hamming_recursive'
 
 class HammingTest < Minitest::Test
   def test_identical_strands
-    skip
     assert_equal 0, Hamming.compute('A', 'A')
   end
 
   def test_long_identical_strands
-    skip
     assert_equal 0, Hamming.compute('GGACTGA', 'GGACTGA')
   end
 
   def test_complete_distance_in_single_nucleotide_strands
-    skip
     assert_equal 1, Hamming.compute('A', 'G')
   end
 
   def test_complete_distance_in_small_strands
-    skip
     assert_equal 2, Hamming.compute('AG', 'CT')
   end
 
   def test_small_distance_in_small_strands
-    skip
     assert_equal 1, Hamming.compute('AT', 'CT')
   end
 
   def test_small_distance
-    skip
     assert_equal 1, Hamming.compute('GGACG', 'GGTCG')
   end
 
   def test_small_distance_in_long_strands
-    skip
     assert_equal 2, Hamming.compute('ACCAGGG', 'ACTATGG')
   end
 
   def test_non_unique_character_in_first_strand
-    skip
     assert_equal 1, Hamming.compute('AGA', 'AGG')
   end
 
   def test_non_unique_character_in_second_strand
-    skip
     assert_equal 1, Hamming.compute('AGG', 'AGA')
   end
 
   def test_large_distance
-    skip
     assert_equal 4, Hamming.compute('GATACA', 'GCATAA')
   end
 
   def test_large_distance_in_off_by_one_strand
-    skip
     assert_equal 9, Hamming.compute('GGACGGATTCTG', 'AGGACGGATTCT')
   end
 
   def test_empty_strands
-    skip
     assert_equal 0, Hamming.compute('', '')
   end
 
   def test_disallow_first_strand_longer
-    skip
     assert_raises(ArgumentError) { Hamming.compute('AATG', 'AAA') }
   end
 
   def test_disallow_second_strand_longer
-    skip
     assert_raises(ArgumentError) { Hamming.compute('ATA', 'AGTG') }
   end
 end