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)

" Test feedkeys() function.

func Test_feedkeys_x_with_empty_string()
  new
  call feedkeys("ifoo\<Esc>")
  call assert_equal('', getline('.'))
  call feedkeys('', 'x')
  call assert_equal('foo', getline('.'))

  " check it goes back to normal mode immediately.
  call feedkeys('i', 'x')
  call assert_equal('foo', getline('.'))
  quit!
endfunc