Module not available in mock do block

[Jamie Evans]

I have a custom module MyApp.MyModule with a function do_something in a compiled file (my_module.ex).

defmodule MyApp.MyModule do
  def do_something(the_something), do: "Doing #{the_something}"
end

And I have a test that is trying to mock the function and see that it was called, but I'm getting an error saying that the module is not available.

defmodule MyApp.MyModuleTest do
  import Mock

  alias MyApp.MyModule

  describe "see if I can mock" do
    test "Try mocking" do
      assert MyModule.do_something("a thing") == "Doing a thing")
      with_mock(MyModule, [do_something: fn(_the_something) -> "Something else" end]) do
        assert MyModule.do_something("another thing") == "Something else"
      end
    end
  end
end

And the error is:

** (UndefinedFunctionError) function MyApp.MyModule.do_something/1 is undefined (module MyApp.MyModule is not available)
     code: MyApp.MyModule.do_something("another thing")
     stacktrace:
       (my_app) MyApp.MyModule.do_something("another thing")
       test/my_app/my_module_tests.exs:10: (test)

As you can see, I can call the function perfectly fine outside of the mock, but if I can't call it inside the mock, it defeats the entire purpose of the mocking tool.

[Daniel Olshansky]

I tried running your test and it passed for me.

There were two tiny syntax changes I had to make:

• Remove closing ) on line 8
• Add use ExUnit.Case

defmodule MyApp.MyModuleTest do
  use ExUnit.Case

  import Mock

  alias MyApp.MyModule

  describe "see if I can mock" do
    test "Try mocking" do
      assert MyModule.do_something("a thing") == "Doing a thing"
      with_mock(MyModule, [do_something: fn(_the_something) -> "Something else" end]) do
        assert MyModule.do_something("another thing") == "Something else"
      end
    end
  end
end

Could you perhaps push a branch where I could try to reproduce it?