My project has existing (relatively low-coverage; maybe 50%, and a couple of them can't actually test the result, only that the process completes) tests using Python's built-in unittest suite. I've worked with hypothesis before and I'd like to use that as well - but I'm not sure I want to throw out the existing tests.
Has anyone tried having two completely separate testing frameworks and test sets on a project? Is this a good idea, or is it going to cause unexpected problems down the line?
IMO, If current framework supports the attribute based categorization then you can separate them by adding separate categories to have separate results from old and new tests. 
On the other hand you can also go for multiple framework if they're supported and have no conflict of interest(E.g. asserts, test reports) by the test runner in your project. But in this case you'll end up having two separate reports from your test executions.
Is it wise to use two completely separate unit testing suites?