Django I knew had pretty weak testing tools compared to Ruby/Rails mostly because the culture was no there. It was way harder to find a Rails App with had little to no tests. Quite a contrary in Django world.

Rails is a Web Framework. I don't understand the point about ML. Those categories are totally different. I guess it might be a tiny plus, but not very practical. Going this route one might conclude that game studios should build Websites in C++?

Because most machine learning models are still deployed behind a web server? For ranking, filtering, recommenders, visual search / nearest neighbor search, NLP, image recognition and etc python is a great first choice.

> I've never used rspec but it sounds like pytest and hypothesis would do the job

Sorry it really does not, having factorybot + rspec + rspec-mocks really is a super power when it comes in testing.

The issue is that most of the time I land on a django project, it has really poor testing whereas most of the time I land on a Rails project, it has very close to complete testing. The reason is that the tests are more tedious to write.

And this culture trickles down to your dependencies as well. Anything you install with rails is almost guaranteed to have the upmost quality of testing.

Testing django with pytest is super easy (ex: https://dev.to/sherlockcodes/pytest-with-django-rest-framewo...)

It's nowhere near as equivalent, where's the behavior testing? Where is stuff like allow_any_instance_of(...).to receive(...).and_return(...)? What about shared examples? How can you patch globally the current time? Where are partial matchers like an_object_having_attributes? What about automatic db rollbacks?

Have a look on the examples here https://github.com/rspec/rspec-mocks

Andrew Kane wrote gems similar to popular ML libraries which are wrappers around C code: https://ankane.org/new-ml-gems

pytorch: https://github.com/ankane/torch.rb Tensorflow: https://github.com/ankane/tensorflow-ruby