TestHarnessis a type that provides an interface to test cases for interacting with functionality under test. For example, a WidgetHarness might provide controls for interacting with and measuring a Widget, allowing us to easily write tests for Widget functionality.
Runs a test in an executor, potentially repeatedly and concurrently
We can run any test which is an async function from some harness
Hto a result
Used to run tests that require TestHarness types as inputs on a singlethreaded executor. This attribute should be used instead of
#[test], not in addition to it.