Either I'm missing something, or the eunit command fails to compile .yrl files when running the test suite.
When running rebar eunit on a clean project (i.e. no previously built beam files around), it fails due to a missing beam file that should've come from compiling a .yrl file (https://travis-ci.org/erlydtl/erlydtl/jobs/20463110).
Workaround for rebar/rebar#247.
As `rebar eunit` doesn't compile .yrl files,
we need to make sure those are already compiled
when running the eunit tests.