commit https://github.com/vim/vim/commit/472472898ab71ac80a86fedc37f8eb91461788dd Author: Bram Moolenaar <Bram@vim.org> Date: Tue Aug 2 22:36:02 2016 +0200 patch 7.4.2146 Problem: Not enough testing for popup menu. CTRL-E does not always work properly. Solution: Add more tests. When using CTRL-E check if the popup menu is visible. (Christian Brabandt)

" 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