Move const tests for Poll to library\core

Part of rust-lang#76268

Author: CDirkx

library/core/tests/lib.rs

@@ -76,5 +76,6 @@ mod result;
 mod slice;
 mod str;
 mod str_lossy;
+mod task;
 mod time;
 mod tuple;

library/core/tests/task.rs

@@ -0,0 +1,14 @@
+use core::task::Poll;
+
+#[test]
+fn poll_const() {
+    // test that the methods of `Poll` are usable in a const context
+
+    const POLL: Poll<usize> = Poll::Pending;
+
+    const IS_READY: bool = POLL.is_ready();
+    assert!(!IS_READY);
+
+    const IS_PENDING: bool = POLL.is_pending();
+    assert!(IS_PENDING);
+}