commit https://github.com/vim/vim/commit/437905c25d4cedfa16d0f87392e4a000d22362b7 Author: Bram Moolenaar <Bram@vim.org> Date: Tue Apr 26 19:01:05 2016 +0200 patch 7.4.1789 Problem: Cannot use ch_read() in the close callback. Solution: Do not discard the channel if there is readahead. Do not discard readahead if there is a close callback.

" 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