Yes. I generally put tests inside the module they are meant to test.
A lot of people point out that you shouldnt test the internals of a module. If the tests are inside the module, then you have the opportunity to test internal implementation details. That seems like a valid point to me, and I keep it in mind, but I like the convenience of writing tests right next to the spot that the code is written. I really like that “side-by-side”-ness. Its also easier to make test data and test functions from within a module.