How will compose ui testing look like? Do you plan to improve Espresso or you will create brand-new testing framework similar to Flutter Driver?

There are already tests in the compose preview, you can have a look at them 🙂

Yes, there is a lot of thought going into providing a good testing story for Compose. The current plan is to provide both some improved Espresso bindings for Compose and also some additional testing libraries that we think will greatly improve the testing of composable functions.