Merge pull request #32 from JonRowe/prevent-kernel-being-an-issue

Prevent default Kernel imports from conflicting with allowed functions

lib/double.ex

@@ -187,6 +187,7 @@ defmodule Double do
     code = Enum.reduce(funcs, code, fn({function_name, func}, acc) ->
       {signature, message} = function_parts(function_name, func)
       acc <> """
+        #{unimport_if_needed(function_name, func)}
         def #{function_name}(#{signature}) do
           #{function_body(mod, message, function_name, signature)}
         end
@@ -211,7 +212,7 @@ defmodule Double do
   defp function_body(double_id, message, function_name, signature) do
     """
     test_pid = Double.Registry.whereis_test(\"#{double_id}\")
-    send(test_pid, #{message})
+    Kernel.send(test_pid, #{message})
     pid = Double.Registry.whereis_double(\"#{double_id}\")
     func_list = Double.func_list(pid)
     Double.FuncList.apply(func_list, :#{function_name}, [#{signature}])
@@ -234,6 +235,12 @@ defmodule Double do
     {signature, message}
   end
 
+  defp unimport_if_needed(function_name, func) do
+    if Enum.member?(Kernel.__info__(:functions), {function_name, func_arity = arity(func)}) do
+      "import Kernel, except: [#{function_name}: #{func_arity}]"
+    end
+  end
+
   defp arity(func) do
     :erlang.fun_info(func)[:arity]
   end

test/double_test.exs

@@ -161,6 +161,14 @@ defmodule DoubleTest do
       assert dbl.loaded_applications() == :ok
     end
 
+    test "can override kernel functions" do
+      dbl =
+        double(TestModule)
+        |> allow(:send, fn _, _ -> :ok end)
+
+      assert dbl.send(:a, :b) == :ok
+    end
+
     test "verifies valid behavior doubles" do
       dbl =
         TestBehaviour

test/support/test_module.ex

@@ -6,4 +6,5 @@ defmodule TestModule do
   def process(x, y, z), do: {x, y, z}
   def another_function, do: nil
   def another_function(x), do: x
+  def send(a, b), do: {a, b}
 end