Add miri support to tests suite

[nurmohammed840]

Many parts of the codebase can be tested with Miri.

However, Miri is not currently compatible with #[tokio::test] , At the moment Miri doesn't support some of the operations used by the runtime.

Solution

To address this, A new configuration miri was added to a custom tokio_test macro. to use this:

mod tokio {
    pub use tokio::*;
    pub use tokio_test_macros::tokio_test as test;
}

When the miri config is not present, it simply adds #[cfg_attr(miri, ignore)] to the test:

#[tokio::test]
async fn test_example() {}

#[test]
#[cfg_attr(miri, ignore)]
fn test_example() { ... }

---

However, when miri config is present, it generates the following code:

#[tokio::test(miri)]
async fn test_example() {}

#[test]
fn test_example() {
    let body = async {};
    if cfg!(miri) {
        // Use any simple thread based executor. For example:
        return future::executor::block_on(body);
    }
    // Otherwise, use the Tokio runtime
    // ...
}

This change DOES NOT affect the existing codebase in any way.