coverage: Extract `executor::block_on` from several async coverage tests

By moving `block_on` to an auxiliary crate, we avoid having to keep a separate
copy of it in every async test.

(This also incorporates some small tweaks to the headers in `await_ready.rs`.)

1 files changed, 19 insertions, 0 deletions

diff --git a/tests/coverage/auxiliary/executor.rs b/tests/coverage/auxiliary/executor.rs
new file mode 100644
index 00000000000..fb07c8ce304
--- /dev/null
+++ b/tests/coverage/auxiliary/executor.rs
@@ -0,0 +1,19 @@
+#![feature(coverage_attribute, noop_waker)]
+//@ edition: 2021
+
+use core::future::Future;
+use core::pin::pin;
+use core::task::{Context, Poll, Waker};
+
+/// Dummy "executor" that just repeatedly polls a future until it's ready.
+#[coverage(off)]
+pub fn block_on<F: Future>(mut future: F) -> F::Output {
+    let mut future = pin!(future);
+    let mut context = Context::from_waker(Waker::noop());
+
+    loop {
+        if let Poll::Ready(val) = future.as_mut().poll(&mut context) {
+            break val;
+        }
+    }
+}