Adding missing assert in iteration test.

Also checking against symbol rather than string.

koans/about_iteration.rb

@@ -3,7 +3,7 @@
 class AboutIteration < EdgeCase::Koan
 
   def test_each_is_a_method_on_arrays
-    [].methods.include?("each")
+    assert_equal __, [].methods.include?(:each)
   end
 
   def test_iterating_with_each