tests fail because product information changes

[ThomasProctor]

I just forked the repo and ran the tests, and unsurprisingly, lots of them fail... because they are dependent on the information about products not changing, but they do.

I'm not sure what the right solution here is. One option is to reduce the checks to type checks, and assume that, while the values might change (which I see a lot of), the presence of attributes will not.