Merge pull request mongodb#222 from 3rf/PYTHON-621

PYTHON-621: Fixed GridOut.read(0) returning string in Python 3

Author: ajdavis

gridfs/grid_file.py

@@ -468,7 +468,7 @@ def read(self, size=-1):
  self._ensure_file()
 
  if size == 0:
- return ""
+ return EMPTY
 
  remainder = int(self.length) - self.__position
  if size < 0 or size > remainder:

test/test_grid_file.py

@@ -74,6 +74,9 @@ def test_basic(self):
  g = GridOut(self.db.fs, f._id)
  self.assertEqual(b(""), g.read())
 
+ # test that reading 0 returns proper type
+ self.assertEqual(b(""), g.read(0))
+
  def test_md5(self):
  f = GridIn(self.db.fs)
  f.write(b("hello world\n"))