ExUnit assert_receive specify module name in message?

Questions / Help
1

I’m writing a test to make sure the correct version of function is called. I’ve got:

defmodule Foo do 
  def query do 
  end
end

and

defmodule Bar do
  def query do 
  end
end

and finally

defmodule Test do 
  def run do 
    case something do 
      true -> Bar.query()
      _ -> Foo.query()
    end
  end
end

In my test I’m doing:

test "something" do 
  Test.run()
  assert_receive :run
end

This fails with

“No message matching :run after 100ms.
The process mailbox is empty.”

Is there a way using ExUnit assert_receive(d) to decide which one was called when I call Test.run() ? I might be just thinking about this the entirely wrong way, I guess.

2

You can send module name from both implementations:

def query do
  send self(), __MODULE__
end

And distinguish them in tests:

assert_receive Foo
assert_receive Bar

But what do you really want to do?

3

I’ve vastly simplified the code for the example, and in my real test I’m trying to make sure that when I call the function being tested, it in turn calls the correct function based on input.

4

Well, without any details it sounds like testing implementation not behaviour.

Jose described several useful techniques in the following article. I hope this could be helpful for you.

1 Like
5

cool, thank you for your help :slight_smile: