From 5c636b128ed40f3ed926d18adb307e01dfc082f8 Mon Sep 17 00:00:00 2001
From: Andy Stewart <boss@airbladesoftware.com>
Date: Thu, 13 Dec 2018 10:50:02 +0000
Subject: [PATCH] Fix handling of buffer consisting only of a newline.

See #510.
---
 autoload/gitgutter/diff.vim |  6 ++++--
 test/test_gitgutter.vim     | 30 ++++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/autoload/gitgutter/diff.vim b/autoload/gitgutter/diff.vim
index 56e63dd..e1bd5a3 100644
--- a/autoload/gitgutter/diff.vim
+++ b/autoload/gitgutter/diff.vim
@@ -374,8 +374,10 @@ endfunction
 function! s:write_buffer(bufnr, file)
   let bufcontents = getbufline(a:bufnr, 1, '$')
 
-  " Special case: empty buffer; do not write an empty line in this case.
-  if len(bufcontents) > 1 || bufcontents != ['']
+  if bufcontents == [''] && line2byte(1) == -1
+    " Special case: empty buffer; do not write an empty line in this case.
+    " A nearly empty buffer of only a newline has line2byte(1) == 1.
+  else
     if getbufvar(a:bufnr, '&endofline')
           \ || (!getbufvar(a:bufnr, '&binary')
           \     && (!exists('+fixendofline') || getbufvar(a:bufnr, '&fixendofline')))
diff --git a/test/test_gitgutter.vim b/test/test_gitgutter.vim
index 5f40d38..2f0c27c 100644
--- a/test/test_gitgutter.vim
+++ b/test/test_gitgutter.vim
@@ -648,3 +648,33 @@ function Test_encoding()
 
   call assert_equal([], s:signs('cp932.txt'))
 endfunction
+
+
+function Test_empty_file()
+  " 0-byte file
+  call system('touch empty.txt && git add empty.txt')
+  edit empty.txt
+
+  call s:trigger_gitgutter()
+  call assert_equal([], s:signs('empty.txt'))
+
+
+  " File consisting only of a newline
+  call system('echo "" > newline.txt && git add newline.txt')
+  edit newline.txt
+
+  call s:trigger_gitgutter()
+  call assert_equal([], s:signs('newline.txt'))
+
+
+  " 1 line file without newline
+  " Vim will force a newline unless we tell it not to.
+  call system('echo -n "a" > oneline.txt && git add oneline.txt')
+  set noeol nofixeol
+  edit! oneline.txt
+
+  call s:trigger_gitgutter()
+  call assert_equal([], s:signs('oneline.txt'))
+
+  set eol fixeol
+endfunction