Open
Description
Currently, most test cases are specified using a (rather inscrutible) tuple of values. Instead, we should make us of a TestCase type everywhere. @mhauru did something like this for the bijectors integration tests. Instead of passing many different kwargs to test_rule, we should pass this data structure.
This will prevent problems such as those encountered by @lukas-weber in #578 , where an important testing option isn't available as part of the test specification.