'Testing conversion to strings'

def testUnitsStr(self):

    a1 = A(sq_m=100)
    a2 = A(sq_km=3.5)
    self.assertEqual(str(a1), '100.0    sq_m')
    self.assertEqual(str(a2), '3.5    sq_km')
    self.assertEqual(repr(a1), 'Area(sq_m=100.0)')
    self.assertEqual(repr(a2), 'Area(sq_km=3.5)')
