use index.unique() vs. np.unique(index)

Author: erbian

pandas/tests/indexes/common.py

@@ -943,7 +943,7 @@ def test_join_self(self, how):
         index = self.create_index()
         joined = index.join(index, how=how)
 
-        if index is np.unique(index):
+        if index is index.unique():
             assert index is joined
 
         else: