Redbug conflicting with cover/excoveralls

[nietaki]

Hi,
I'm migrating rexbug to redbug 2.x and I already made the changes to get the basics up and running correctly.

The problem I ran into is that while all the tests run correctly, they fail when running the tests with excoveralls - it seems like redbug isn't able to extract the module/function info for Elixir modules that aren't part of the standard library.

Repro here.

With an elixir module Foo.Bar being defined:

defmodule Foo do
  @moduledoc false
  defmodule Bar do
    @moduledoc false
    def abc() do
    end

    def xyz(_a, _b, _c) do
    end
  end
end

running redbug against it fails:

{:argument_error, :no_matching_functions} = :redbug.start('\'Elixir.Foo.Bar\'')

I verified it's not related the module not being compiled in the test environment or being part of test/support/ as opposed to the main lib/

I suspect that it's caused by coveralls messing with the compilation / code loading, but I don't understand what's happening exactly. I checked that the :cover compile path (as it is used inside coveralls) is included in :code.get_path() and it is - making sure it's the first path in the list doesn't change anything.

If anyone has an idea what can be done (whether is a change to my approach, or patching either coveralls or redbug) so that I can keep the code coverage, I'd appreciate it.

[nietaki]

To narrow down the search I replaced ExCoveralls with Mix test.coverage, which uses cover underneath, and the results are the same:

$ mix test test/redbug_repro.exs --cover                                                                                                                                                                                                                                                    2 ↵
Cover compiling modules ...


  1) test base redbug invocation (RexbugIntegrationTest)
     test/redbug_repro.exs:11
     {:argument_error, :no_matching_functions}
     code: assert is_integer(i), inspect({i, p})
     stacktrace:
       test/redbug_repro.exs:13: (test)

.
Finished in 0.06 seconds (0.00s async, 0.06s sync)
2 tests, 1 failure