Vendor dependencies

Let's see how I like this workflow.

vendor/tokio/tests/io_driver_drop.rs

@@ -0,0 +1,54 @@
+#![warn(rust_2018_idioms)]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi does not support bind
+
+use tokio::net::TcpListener;
+use tokio::runtime;
+use tokio_test::{assert_err, assert_pending, assert_ready, task};
+
+#[test]
+fn tcp_doesnt_block() {
+    let rt = rt();
+
+    let listener = {
+        let _enter = rt.enter();
+        let listener = std::net::TcpListener::bind("127.0.0.1:0").unwrap();
+        TcpListener::from_std(listener).unwrap()
+    };
+
+    drop(rt);
+
+    let mut task = task::spawn(async move {
+        assert_err!(listener.accept().await);
+    });
+
+    assert_ready!(task.poll());
+}
+
+#[test]
+fn drop_wakes() {
+    let rt = rt();
+
+    let listener = {
+        let _enter = rt.enter();
+        let listener = std::net::TcpListener::bind("127.0.0.1:0").unwrap();
+        TcpListener::from_std(listener).unwrap()
+    };
+
+    let mut task = task::spawn(async move {
+        assert_err!(listener.accept().await);
+    });
+
+    assert_pending!(task.poll());
+
+    drop(rt);
+
+    assert!(task.is_woken());
+    assert_ready!(task.poll());
+}
+
+fn rt() -> runtime::Runtime {
+    runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()
+        .unwrap()
+}