test/pybind/test_rados.py: expand test_xattrs/test_obj_xattrs

to cover attribute with empty value case.

Signed-off-by: Gu Zhongyan <guzhongyan@360.cn>
(cherry picked from commit b79107d)

src/test/pybind/test_rados.py

@@ -369,7 +369,7 @@ def test_list_ns_objects(self):
                 ('ns1', 'ns1-c'), ('ns1', 'ns1-d')])
 
     def test_xattrs(self):
-        xattrs = dict(a=b'1', b=b'2', c=b'3', d=b'a\0b', e=b'\0')
+        xattrs = dict(a=b'1', b=b'2', c=b'3', d=b'a\0b', e=b'\0', f='')
         self.ioctx.write('abc', b'')
         for key, value in xattrs.items():
             self.ioctx.set_xattr('abc', key, value)
@@ -380,7 +380,7 @@ def test_xattrs(self):
         eq(stored_xattrs, xattrs)
 
     def test_obj_xattrs(self):
-        xattrs = dict(a=b'1', b=b'2', c=b'3', d=b'a\0b', e=b'\0')
+        xattrs = dict(a=b'1', b=b'2', c=b'3', d=b'a\0b', e=b'\0', f='')
         self.ioctx.write('abc', b'')
         obj = list(self.ioctx.list_objects())[0]
         for key, value in xattrs.items():