def test_union(self):
"Test union of two SimpleBitfields."
field = SimpleBitfield('110011')
field.union(SimpleBitfield('001100'))
self.assertEqual(field._d, int('111111', 2))
field = SimpleBitfield('000011')
field.union(SimpleBitfield('001100'))
self.assertEqual(field._d, int('001111', 2))
field = SimpleBitfield('010010')
field.union(SimpleBitfield('011110'))
self.assertEqual(field._d, int('011110', 2))
