update test case

Author: chfw

tests/base.py

@@ -107,7 +107,7 @@ def test_iterate_through_sheets(self):
         for s in b:
             data = pyexcel.utils.to_array(s)
             assert self.content[s.name] == data
-        si = pyexcel.sheets.iterators.SheetIterator(b)
+        si = pyexcel.iterators.SheetIterator(b)
         for s in si:
             data = pyexcel.utils.to_array(s)
             assert self.content[s.name] == data