commit https://github.com/vim/vim/commit/3056735ae8a366aa7fcb51872520895251858637 Author: Bram Moolenaar <Bram@vim.org> Date: Sat Aug 27 21:25:44 2016 +0200 patch 7.4.2273 Problem: getwininfo() and getbufinfo() are inefficient. Solution: Do not make a copy of all window/buffer-local options. Make it possible to get them with gettabwinvar() or getbufvar().

" Test for joining lines.

func Test_join_with_count()
  new
  call setline(1, ['one', 'two', 'three', 'four'])
  normal J
  call assert_equal('one two', getline(1))
  %del
  call setline(1, ['one', 'two', 'three', 'four'])
  normal 10J
  call assert_equal('one two three four', getline(1))
  quit!
endfunc