commit https://github.com/vim/vim/commit/f1b512a0b62d0fa47ee9b2612556f375e1f22fc2 Author: Bram Moolenaar <Bram@vim.org> Date: Thu Sep 1 20:50:54 2016 +0200 patch 7.4.2302 Problem: Default interface versions for MS-Windows are outdated. Solution: Use Active Perl 5.24, Python 3.5.2. Could only make it work with Ruby 1.9.2.

" 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