Unit testing "templates"?

[Raymond Hettinger]

"Francis Avila"
> I'm now writing tests for these methods which instantiate the class with
> known data and then call a method of that instance to get a known result.
> But it's getting repetitive, and I'm wondering if there is a better way.>

Whenever you're doing something repetitive, there's *always* a
better way.  For a good example, take a look at test_sets.py in Py2.3.
It takes advantage of inheritance to factor out common code.  In your
example, it would look like this (untested code ahead):

class DatatypeUnpack(unittest.TestCase):
    """Verify xdmcplib.Unpacker conversions."""
    def testUnpack(self):
        # unpack should return known result from known valid input
        for value, data in self.vdpairs:
            obj = xdmcplib.Unpacker(data)
            result = getattr(obj, self.method)()
            self.assertEqual(value, result)

Class DatatypeUnpackCard32(DatatypeUnpack):
    vdpairs = ( (0,'\x00\x00\x00\x00'), (1,'\x00\x00\x00\x01'),
                              (2,'\x00\x00\x00\x02'),
                              (65535,'\x00\x00\xff\xff'),
                             (4294967295L,'\xff\xff\xff\xff') )
    method = "unpack_card32"

Class DatatypeUnpackArray8(DatatypeUnpack):
    vdpairs = ( ('','\x00\x00'), ('Test','\x00\x04Test') )
    method = "unpack_array8"


Raymond Hettinger