Demand code and/or data as a condition of peer review?
I would suggest first spending a little bit of time reflecting to yourself on why you want to see sharing of code and data, and which code and data you would want to be shared.  Is it more ideological in nature ("information wants to be free"), or at its root is it a belief more about scientific ethics and efficacy?

I am almost certain that you do not actually want all data and code to be shared.  For example, you probably do not want identifying information about subjects to be shared.  Likewise, you probably do not care too much about little bits of utility code that don't have anything much to do with the science.  Where do you draw your boundaries and why?

The reason I would suggest doing that, is that you will then be in a good position, as a reviewer, to persuasively argue for the inclusion of code and/or data for objective reasons that the editor and author are more likely to agree with, even if their personal preferences are different.  I don't think you'll have much effect by refusing to review (unless you can get a lot of colleagues to exert pressure along with you), but I think you may make much more difference by refusing to accept poorly justified conclusions in the absence of result and method information to support them.