def test__sub__KnownValues(self):
        #__sub__ should give known result with known input
        #commuting the input should result in equal magnitude, opposite sign

        x=units.NumberDict()
        y=units.NumberDict()
        x['t1'],x['t2']= 1,2
        y['t1'],y['t2']= 2,1
        result1,result2=x-y,y-x
        self.assertEqual((-1,1), (result1['t1'],result1['t2']))
        self.assertEqual((1,-1), (result2['t1'],result2['t2']))
dataset/ETHPy150Open OpenMDAO/OpenMDAO-Framework/openmdao.units/openmdao/units/test/test_units.py/test_NumberDict.test__sub__KnownValues/original