Before:
  let g:pre_success = 0
  let g:post_success = 0
  let g:ale_run_synchronously = 1

After:
  let g:ale_run_synchronously = 0
  let g:ale_buffer_info = {}
  augroup! VaderTest

Execute (Run a lint cycle, and check that a variable is set in the autocmd):
  augroup VaderTest
    autocmd!
    autocmd User ALELintPre let g:pre_success = 1
    autocmd User ALELintPost let g:post_success = 1
  augroup end

  call ale#Lint()

  AssertEqual g:pre_success, 1
  AssertEqual g:post_success, 1