commit https://github.com/vim/vim/commit/58adb14739fa240ca6020cede9ab1f1cb07bd90a Author: Bram Moolenaar <Bram@vim.org> Date: Sat Jan 16 21:50:51 2016 +0100 patch 7.4.1108 Problem: Expanding "~" halfway a file name. Solution: Handle the file name as one name. (Marco Hinz) Add a test. Closes https://github.com/vim/vim/issues/564.

Tests for writefile()

STARTTEST
:source small.vim
:%delete _
:let f = tempname()
:call writefile(["over","written"], f, "b")
:call writefile(["hello","world"], f, "b")
:call writefile(["!", "good"], f, "a")
:call writefile(["morning"], f, "ab")
:call writefile(["", "vimmers"], f, "ab")
:bwipeout!
:$put =readfile(f)
:1 delete _
:w! test.out
:qa!
ENDTEST