commit https://github.com/vim/vim/commit/ac105ed3c420660ddbddc501c97875c48220817e Author: Bram Moolenaar <Bram@vim.org> Date: Thu Jul 21 20:33:32 2016 +0200 patch 7.4.2086 Problem: Using the system default encoding makes tests unpredictable. Solution: Always use utf-8 or latin1 in the new style tests. Remove setting encoding and scriptencoding where it is not needed.

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
:call delete(f)
:qa!
ENDTEST