add readline to GridOut PYTHON-157

gridfs/grid_file.py

@@ -390,6 +390,22 @@ class GridOut(object):
         self.__buffer = data[size:]
         return to_return
 
+    def readline(self, size=-1):
+        """Read one line or up to `size` bytes from the file.
+
+        :Parameters:
+         - `size` (optional): the maximum number of bytes to read
+
+        .. versionadded:: 1.8.1+
+        """
+        bytes = ""
+        while len(bytes) != size:
+            byte = self.read(1)
+            bytes += byte
+            if byte == "" or byte =="\n":
+                break
+        return bytes
+
     def tell(self):
         """Return the current position of this file.
         """

test/test_grid_file.py

@@ -367,6 +367,24 @@ class TestGridFile(unittest.TestCase):
         self.assertEqual("d", g.read(2))
         self.assertEqual("", g.read(2))
 
+    def test_readline(self):
+        f = GridIn(self.db.fs, chunkSize=5)
+        f.write("""Hello world,
+How are you?
+Hope all is well.
+Bye""")
+        f.close()
+
+        g = GridOut(self.db.fs, f._id)
+        self.assertEqual("H", g.read(1))
+        self.assertEqual("ello world,\n", g.readline())
+        self.assertEqual("How a", g.readline(5))
+        self.assertEqual("", g.readline(0))
+        self.assertEqual("re you?\n", g.readline())
+        self.assertEqual("Hope all is well.\n", g.readline(1000))
+        self.assertEqual("Bye", g.readline())
+        self.assertEqual("", g.readline())
+
     def test_iterator(self):
         f = GridIn(self.db.fs)
         f.close()