patch 8.1.1775: error message may be empty in filetype test commit https://github.com/vim/vim/commit/eee9f65b2a213e9031f172d9d3b22adad6cb985d Author: Bram Moolenaar <Bram@vim.org> Date: Mon Jul 29 21:14:42 2019 +0200 patch 8.1.1775: error message may be empty in filetype test Problem: Error message may be empty in filetype test. Solution: Use v:exception instead. (Daniel Hahler, closs https://github.com/vim/vim/issues/4744)

" Tests for :undo

func Test_ex_undo()
  new ex-undo
  setlocal ul=10
  exe "normal ione\n\<Esc>"
  setlocal ul=10
  exe "normal itwo\n\<Esc>"
  setlocal ul=10
  exe "normal ithree\n\<Esc>"
  call assert_equal(4, line('$'))
  undo
  call assert_equal(3, line('$'))
  undo 1
  call assert_equal(2, line('$'))
  undo 0
  call assert_equal(1, line('$'))
  quit!
endfunc