chore: checkpoint before Python removal

vendor/futures/tests/future_select_all.rs

@@ -0,0 +1,25 @@
+use futures::executor::block_on;
+use futures::future::{ready, select_all};
+use std::collections::HashSet;
+
+#[test]
+fn smoke() {
+    let v = vec![ready(1), ready(2), ready(3)];
+
+    let mut c = vec![1, 2, 3].into_iter().collect::<HashSet<_>>();
+
+    let (i, idx, v) = block_on(select_all(v));
+    assert!(c.remove(&i));
+    assert_eq!(idx, 0);
+
+    let (i, idx, v) = block_on(select_all(v));
+    assert!(c.remove(&i));
+    assert_eq!(idx, 0);
+
+    let (i, idx, v) = block_on(select_all(v));
+    assert!(c.remove(&i));
+    assert_eq!(idx, 0);
+
+    assert!(c.is_empty());
+    assert!(v.is_empty());
+}