def test_map(self):
m = FieldFilter(drop=["a","c"])
self.assertListEqual(["b", "d"], m.filter(self.fields).names())
m = FieldFilter(keep=["a","c"])
self.assertListEqual(["a", "c"], m.filter(self.fields).names())
m = FieldFilter(rename={"a":"x","c":"y"})
self.assertListEqual(["x", "b", "y", "d"], m.filter(self.fields).names())
