ExUnit issues with Protocol

Questions / Help
,
1

My directory structure is:
lib/expr/interp.ex
lib/expr.ex

where interp.ex is a protocol with implementation which uses expr.ex.

I have a interp_test.exs and when I run “mix test” the errors results:

** (FunctionClauseError) no function clause matching in IO.chardata_to_string/1
(elixir) lib/io.ex:445: IO.chardata_to_string(nil)
(elixir) lib/path.ex:289: Path.relative_to/2
test/interp_test.exs:5: (module)
(elixir) lib/code.ex:370: Code.require_file/2
(elixir) lib/kernel/parallel_require.ex:57: anonymous fn/2 in Kernel.ParallelRequire.spawn_requires/5

===============
The first 5 lines of the interp_test.exs is:

require Expr.Interp

defmodule InterpTest do
use ExUnit.Case
doctest Expr.Interp

=================

I marked this as an issue with Protocol because before I changed to Protocols the tests work without issues. Before Protocol interp was a Module with one function.

Thanks

2

Can you paste the complete/relevant code here on in a GitHub Gist? That would make it easier to figure out what’s wrong.

3

With protocols the most common reason for this kind of behaviour is because of protocol consolidation. Try adding the following to your mix.exs's project definition:

def project do                                                          
  [                                                                     
    app: ...
    consolidate_protocols: Mix.env() != :test,

This makes sure that protocols are not consolidated at compile time in your test env.

However, I am just guessing. Please share your full code so that we can debug it better :slight_smile:

1 Like
4

That did the trick. “mix test” works as expected. Thanks for your help.

1 Like