(UndefinedFunctionError) function HTTPoison.request/5 is undefined (module HTTPoison is not available

Questions & Help Questions
,
3 
$ elixir --version
Erlang/OTP 20 [erts-9.2] [source] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:10] [kernel-poll:false]

Elixir 1.7.4 (compiled with Erlang/OTP 20)

BTW, this is the highest version I can use. (project’s travis.yml uses 1.5.3/1.6.5)

I tried rm -rf _build followed directly by mix test test/gateways/mercadopago_test.exs

Same results :cry: