Execute(Open a file some directory down):
  silent! cd /testplugin/test
  :e! top/middle/bottom/dummy.txt

Then(We should be able to find the right directory):
  AssertEqual
  \ expand('%:p:h:h:h:h') . '/top/ale-special-directory-name-dont-use-this-please/',
  \ ale#util#FindNearestDirectory(bufnr('%'), 'ale-special-directory-name-dont-use-this-please')

Execute(Do nothing):

Then(We shouldn't find anything for files which don't match):
  AssertEqual
  \ '',
  \ ale#util#FindNearestDirectory(bufnr('%'), 'ale-this-should-never-match-anything')