Add test for staging subsequent nearby hunk.

test/helper.vim

@@ -12,6 +12,11 @@ function! DumpSigns(filename)
   redir END
 endfunction
 
+function! DumpGitDiff(filename)
+  call system('git diff fixture.txt > '.a:filename.'.actual')
+endfunction
+
 function! DumpGitDiffStaged(filename)
   call system('git diff --staged fixture.txt > '.a:filename.'.actual')
 endfunction
+

test/hunkStageNearbyGitDiff.expected

@@ -0,0 +1,13 @@
+diff --git a/test/fixture.txt b/test/fixture.txt
+index 53b13df..8fdfda7 100644
+--- a/test/fixture.txt
++++ b/test/fixture.txt
+@@ -1,5 +1,8 @@
+ a
+ b
++x
++y
++z
+ c
+ e
+ f

test/hunkStageNearbyGitDiffStaged.expected

@@ -0,0 +1,12 @@
+diff --git a/test/fixture.txt b/test/fixture.txt
+index f5c6aff..53b13df 100644
+--- a/test/fixture.txt
++++ b/test/fixture.txt
+@@ -1,7 +1,6 @@
+ a
+ b
+ c
+-d
+ e
+ f
+ g

test/hunkStageNearbySigns.expected

@@ -0,0 +1,6 @@
+
+--- Signs ---
+Signs for fixture.txt:
+    line=3  id=3000  name=GitGutterLineAdded
+    line=4  id=3001  name=GitGutterLineAdded
+    line=5  id=3002  name=GitGutterLineAdded

test/testHunkStageNearbyHunk.vim

@@ -0,0 +1,10 @@
+source helper.vim
+call Setup()
+
+execute "normal! 2Gox\<CR>y\<CR>z"
+normal 2jdd
+normal k
+execute 'GitGutterStageHunk'
+call DumpSigns('hunkStageNearbySigns')
+call DumpGitDiff('hunkStageNearbyGitDiff')
+call DumpGitDiffStaged('hunkStageNearbyGitDiffStaged')