fn assert_unmoved(self) -> AssertUnmoved<Self>
    where
        Self: Sized,
    {
        AssertUnmoved::new(self)
    }
Asserts that the given is not moved after being polled.

A check for movement is performed each time the future is polled
and when `Drop` is called.

Aside from keeping track of the location at which the future was first
polled and providing assertions, this future adds no runtime behavior
and simply delegates to the child future.
futures-test/src/future/mod.rs