Vendor dependencies

Let's see how I like this workflow.

vendor/tokio/tests/fs_file.rs

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+#![warn(rust_2018_idioms)]
+#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi does not support file operations
+
+use std::io::prelude::*;
+use tempfile::NamedTempFile;
+use tokio::fs::File;
+use tokio::io::{AsyncReadExt, AsyncSeekExt, AsyncWriteExt, SeekFrom};
+use tokio_test::task;
+
+const HELLO: &[u8] = b"hello world...";
+
+#[tokio::test]
+async fn basic_read() {
+    let mut tempfile = tempfile();
+    tempfile.write_all(HELLO).unwrap();
+
+    let mut file = File::open(tempfile.path()).await.unwrap();
+
+    let mut buf = [0; 1024];
+    let n = file.read(&mut buf).await.unwrap();
+
+    assert_eq!(n, HELLO.len());
+    assert_eq!(&buf[..n], HELLO);
+}
+
+#[tokio::test]
+async fn basic_write() {
+    let tempfile = tempfile();
+
+    let mut file = File::create(tempfile.path()).await.unwrap();
+
+    file.write_all(HELLO).await.unwrap();
+    file.flush().await.unwrap();
+
+    let file = std::fs::read(tempfile.path()).unwrap();
+    assert_eq!(file, HELLO);
+}
+
+#[tokio::test]
+async fn basic_write_and_shutdown() {
+    let tempfile = tempfile();
+
+    let mut file = File::create(tempfile.path()).await.unwrap();
+
+    file.write_all(HELLO).await.unwrap();
+    file.shutdown().await.unwrap();
+
+    let file = std::fs::read(tempfile.path()).unwrap();
+    assert_eq!(file, HELLO);
+}
+
+#[tokio::test]
+async fn rewind_seek_position() {
+    let tempfile = tempfile();
+
+    let mut file = File::create(tempfile.path()).await.unwrap();
+
+    file.seek(SeekFrom::Current(10)).await.unwrap();
+
+    file.rewind().await.unwrap();
+
+    assert_eq!(file.stream_position().await.unwrap(), 0);
+}
+
+#[tokio::test]
+async fn coop() {
+    let mut tempfile = tempfile();
+    tempfile.write_all(HELLO).unwrap();
+
+    let mut task = task::spawn(async {
+        let mut file = File::open(tempfile.path()).await.unwrap();
+
+        let mut buf = [0; 1024];
+
+        loop {
+            let _ = file.read(&mut buf).await.unwrap();
+            file.seek(std::io::SeekFrom::Start(0)).await.unwrap();
+        }
+    });
+
+    for _ in 0..1_000 {
+        if task.poll().is_pending() {
+            return;
+        }
+    }
+
+    panic!("did not yield");
+}
+
+fn tempfile() -> NamedTempFile {
+    NamedTempFile::new().unwrap()
+}
+
+#[tokio::test]
+#[cfg(unix)]
+async fn unix_fd() {
+    use std::os::unix::io::AsRawFd;
+    let tempfile = tempfile();
+
+    let file = File::create(tempfile.path()).await.unwrap();
+    assert!(file.as_raw_fd() as u64 > 0);
+}
+
+#[tokio::test]
+#[cfg(windows)]
+async fn windows_handle() {
+    use std::os::windows::io::AsRawHandle;
+    let tempfile = tempfile();
+
+    let file = File::create(tempfile.path()).await.unwrap();
+    assert!(file.as_raw_handle() as u64 > 0);
+}