test and are executed in alphabetical order
(but they shouldn't have dependencies). Helper files start with
helper and loaded before any tests are run.test_dir(path, filter = NULL, reporter = "summary", env = test_env(), ...)NULL, only tests with file names matching this
regular expression will be executed. Matching will take on the file
name after it has been stripped of "test-" and ".r".grepl to control filtering.