Show how to test koans for Equalities

lib/ast_manger.ex

@@ -1,24 +0,0 @@
-defmodule ASTMangler do
-  def expand([do: thing], replacement) do
-    [do: expand(thing, replacement)]
-	end
-
-  def expand({fun, context, args}, replacement) do
-    new_args = replace(args, replacement)
-    {fun, context, new_args}
-  end
-
-  def replace(args, b) do
-    args
-    |> Enum.find_index(fn(x) -> x == :__ end)
-    |> replace(args, b)
-  end
-
-	def replace(nil, [], _b), do: []
-	def replace(nil, [ast], b) do
-    [expand(ast,b)]
-	end
-  def replace(index, list, b) do
-    List.update_at(list, index, fn(_)-> b end)
-  end
-end

lib/ast_mangler.ex

@@ -9,6 +9,7 @@ defmodule ASTMangler do
   end
   def expand(n, _), do: n
 
+  def replace(nil, _), do: nil
   def replace(args, b) do
     args
     |> Enum.find_index(fn(x) -> x == :__ end)

lib/koans.ex

@@ -1,8 +1,7 @@
 defmodule Koans do
   defmacro koan(name, body) do
     compiled_name = String.to_atom(name)
-    x = quote do: answer
-    mangled_body = ASTMangler.expand(body, x)
+    mangled_body = ASTMangler.expand(body, quote do: answer)
     quote do
       @koans unquote(compiled_name)
       def unquote(compiled_name)(answer \\ :nothing) do

lib/runner.ex

@@ -40,13 +40,6 @@ defmodule Runner do
     end
   end
 
-  def test_single_koan(module, name, answer) do
-    case apply(module, name, [answer]) do
-      :ok -> :passed
-      error -> IO.inspect error
-    end
-  end
-
   def run_koan(module, name) do
     case apply(module, name, []) do
       :ok   -> :passed