The example of a "bad" rust application is literally how any Axum application is written. I don't have the time to go look, but I'm pretty sure that the Axum examples are written as well. There's nothing wrong with it.

If you want to test, test at the integration layer using testcontainers[0] or something. Not everything has to resemble a Spring style dependency injection/inversion of control.

[0] https://github.com/testcontainers/testcontainers-rs