How to start lager before running eunit test with rebar

Question

I want to start lager before any eunit test is executed so that I can see the log when the tests are actually run (I use the log for debugging purposes).

However I have hundreds of tests (spread across multiple apps and modules) and I don't want to go through every single one and put lager:start() at the beginning so I was wondering if there is a way to tell rebar (or eunit) to execute lager:start() before executing the eunit tests?

Answer 1

I think you can use erl params like "-s lager", and pass it by method are described in following post.

passing runtime arguments to erlang when running rebar eunit

Answer 2

(I know this isn't a full answer, but I agree with Svetlin that there should be a more elegant approach... I'll offering this as an incremental improvement on Petr's answer)

If you use a Makefile with rebar, you could modify the make target to set this environment variable, it'd be something like:

$ make test

or

$ make localtest

And that target would look like:

test:
        ERL_AFLAGS="-s lager" 
        $(REBAR) skip_deps=true eunit