fix pep8

Author: charlesdong1991

pandas/tests/sparse/frame/test_frame.py

@@ -163,7 +163,7 @@ def test_construct_unmatched_sparsedataframe(self, float_frame):
         N = len(sp)
         msg = 'Length of values does not match length of index'
         with pytest.raises(ValueError, match=msg):
-            sp['foo'] = np.random.randn(N-1)
+            sp['foo'] = np.random.randn(N - 1)
 
     # GH 9272
     def test_constructor_empty(self):