auto_test_package fails when tests are in tests/testthat/

[dlebauer]

auto_test_package() does not work with new recommended practice of using tests/testthat from the advanced R book

example:

$ git clone git@github.com:hadley/plyr ## uses inst/tests/ and works
$ R
> testthat::auto_test_package("plyr")
> q()
$ mkdir plyr/tests/testthat/
$ mv plyr/inst/tests/* plyr/tests/testthat/
$ R
> testthat::auto_test_package("plyr")

gives error:

Error in digest(path, file = TRUE) : 
  The specified pathname is not a file: /home/dlebauer/dev/plyr/tests/testthat

While I am at it - unless there is a reason not to , it would be convenient / intuitive if the default path for auto_test_package() were "." to be consistent with the devtools function test() (unless there is a reason not to have a default)

[hadley]

I think auto_test_package() needs to be rewritten to use devtools::load_all().