Improving the examples - adding tests

[szabgab]

Looking at the examples in the examples folder I see that many don't come with tests.
Having tests with the examples will both help make sure that they stay correct as axum changes and it will help the would be developers to learn how to test.

As I see many of the examples have

async fn main() {
   ...
   let app = Router::new()
   ...
}

This, as far as I understand, makes it impossible to use the router in the tests. So I think it would be a good idea to refactor these examples to defined a function

fn app() -> Router {
}

and then write

async fn main() {
   ...
   let app: Router = app();
   ...
}

I'd be happy to do this work for some of the examples, but I'd like to know if you even consider this a good idea.

[jplatte]

We have two testing examples. I think the noise and maintenance effort of adding tests to all examples would be bigger than the benefit.

[yanns]

For people who would like starting contributing, it can be a nice way to add tests for one example. Step by step, we could reach completion.