Make successful non-defaulting onCreate integration tests less verbose

We have a great deal of onCreate tests which expect the object to be created exactly as specified without modification. We currently require these tests to specify identical values for `initial` and `expected`. In the common case where they are identical, this makes the tests more error-prone to write and validate visually. It would be simpler if it were permitted to omit one of these values if it should be identical to the other. I recommend that we allow `expected` to be omitted. If omitted, we default it to the value of `initial`. Similarly for onUpdate tests, we could default the value of `expected` to the value of `updated`.