fix: don't remove behaviour_info/1 from behaviour modules (#105)

Author: escobera

lib/mimic/module.ex

@@ -119,7 +119,9 @@ defmodule Mimic.Module do
     mimic_functions = generate_mimic_functions(module)
     mimic_macros = generate_mimic_macros(module)
     mimic_struct = generate_mimic_struct(module)
+
     quoted = [mimic_info, mimic_struct | mimic_behaviours ++ mimic_functions ++ mimic_macros]
+
     Module.create(module, quoted, Macro.Env.location(__ENV__))
     module
   end
@@ -175,16 +177,11 @@ defmodule Mimic.Module do
 
   defp generate_mimic_functions(module) do
     internal_functions = [__info__: 1, module_info: 0, module_info: 1]
-
-    functions =
-      if function_exported?(module, :__info__, 1) do
-        module.__info__(:functions)
-      else
-        module.module_info(:exports)
-      end
+    macro_functions = macro_functions(module)
+    functions = module.module_info(:exports)
 
     for {fn_name, arity} <- functions,
-        {fn_name, arity} not in internal_functions do
+        {fn_name, arity} not in (internal_functions ++ macro_functions) do
       args = Macro.generate_arguments(arity, module)
 
       quote do
@@ -195,6 +192,16 @@ defmodule Mimic.Module do
     end
   end
 
+  defp macro_functions(module) do
+    if function_exported?(module, :__info__, 1) do
+      :macros
+      |> module.__info__()
+      |> Enum.map(fn {name, arity} -> {String.to_atom("MACRO-#{name}"), arity + 1} end)
+    else
+      []
+    end
+  end
+
   defp generate_mimic_macros(module) do
     macros =
       if function_exported?(module, :__info__, 1) do

test/mimic_test.exs

@@ -1006,6 +1006,8 @@ defmodule Mimic.Test do
   end
 
   describe "behaviours" do
+    setup :set_mimic_private
+
     test "copies behaviour attributes" do
       behaviours =
         Calculator.module_info(:attributes)
@@ -1015,6 +1017,15 @@ defmodule Mimic.Test do
       assert AddAdapter in behaviours
       assert MultAdapter in behaviours
     end
+
+    test "Regression test for PR #105: doesn't remove behaviour_info/1" do
+      Mimic.copy(MultAdapter)
+
+      stub(MultAdapter)
+      expect(MultAdapter, :behaviour_info, fn :callbacks -> [mult: 2] end)
+
+      assert MultAdapter.behaviour_info(:callbacks) == [mult: 2]
+    end
   end
 
   describe "copy/1 with duplicates" do