I fixed a number of them on my previous pull request #10457. There are more. Probably a lot more. I don't recall what exactly this was needed for, but it was persistent and very reproducible. 

> "Any Rails tests should be able to run in any order."

They key word there is "should" and I totally agree, but in reality it isn't true right now. See 9342492e1445c47b02db392ba8430ecb9218fc47 and test/unit.rb before it. Rails tests have been running in sorted order (both class and method) for ages and order dependency bugs have crept in over time.

@tenderlove and I have been talking about taking a second pass at retiring this code and the `test_order` code below it after this gets merged. But some extra planning and dialog will be needed before we can really execute on that because any change we do at this level will affect user tests too. Our first pass will be to override the sorted order for just the rails tests and see how much work it is to excise the bugs. #10457 was a PITA to hunt down, but once I figured out what it was, it was pretty easy to write a temporary teardown that would detect non-default state and raise. Once that was in place, it was a matter of minutes to clean them up. (they need a refactoring too--a helper method would do wonders). More of that will probably have to happen to get the rails tests truly order-independent.