self replicate

[staltz]

How does this new test file differ from resync?

[mixmix]

@staltz may not be different - I didn't know what all the test here were initially (resync didn't jump out). Also writing this test was a very good way to get familiar with the module.

Happy to close if it's the dsame

[staltz]

It's testing the same thing, but in (somewhat) different ways. Perhaps we can leave it out, because the ideal test suite is small (takes less time to read tests and manage/update tests) while covering all the use cases.