Cataclysmic variable evolution: observational tests

We show that future X-ray sky surveys are likely to provide a greatly extended sample of AM Her systems. These will allow a clear decision between evolutionary pictures in which the systems cross the CV period gap and those in which they do not. In the former case the distribution at orbital periods > 4 hr will indicate whether or not AM Her systems are usually born as intermediate polars. We discuss further observational constraints on the angular momentum loss mechanisms driving the evolution, and on the discovery probability for these systems. (author)