The tests are written in an unusual way so that the same tests can be re-used for different fixture configurations (pinned/unpinned and prefetch/no-prefetch). However, we'd like to re-use the fixtures in other test files, and the test pattern makes that very difficult to tease apart the tests from the fixtures. We should consider whether all the combination testing is really needed, and if there's a better pattern that'd allow for easier reuse of the fixtures.