test_binop.py says that it tests binary operators on subtypes of built-in types, but in fact largely focuses on testing its own class Rat, which simply inherits from object and is, essentially, just a simple implementation of fractions.Fraction.

Instead of doing mostly redundant tests here and there it might be better to merge this part (up to line 305) of test_binop.py into test_fractions.py, then maybe add tests of subtypes of built-in types other than just object to test_binop.py.

This requires quite a bit of work though for a relatively minor improvement so do you think it's worth the effort ?

Yeah it would be good to put related tests in the one place.

I was trying to find a good place to test how the comparison operators invoke the __eq__(), __gt__() etc methods, and the existing tests seem to be spread over test_compare.py and test_binop.py.

> This requires quite a bit of work though for a relatively minor improvement so do you think it's worth the effort ?

If you factorize code of unit tests, I expect better tests and more tests, so yes, it's valuable.

But since this issue is old (no activity last 2 years), I close the issue.

Please come back with a reviewable patch (reopen the issue, or open a new one, it's up to you), so it will be easier to discuss. The patch doesn't have to be complete, you can start by factorizing a single function just to discuss the principle and then complete the patch.

Note: I added our fractions experts to the issue while closing it :-)