io: move into `tokio` crate (#1691)

A step towards collapsing Tokio sub crates into a single `tokio`
crate (#1318).

The `io` implementation is now provided by the main `tokio` crate.
Functionality can be opted out of by using the various net related
feature flags.

1 files changed, 46 insertions, 0 deletions

diff --git a/tokio/tests/io_write.rs b/tokio/tests/io_write.rs
new file mode 100644
index 00000000..733b38c9
--- /dev/null
+++ b/tokio/tests/io_write.rs
@@ -0,0 +1,46 @@
+#![warn(rust_2018_idioms)]
+
+use tokio::io::{AsyncWrite, AsyncWriteExt};
+use tokio_test::assert_ok;
+
+use bytes::BytesMut;
+use std::io;
+use std::pin::Pin;
+use std::task::{Context, Poll};
+
+#[tokio::test]
+async fn write() {
+    struct Wr {
+        buf: BytesMut,
+        cnt: usize,
+    }
+
+    impl AsyncWrite for Wr {
+        fn poll_write(
+            mut self: Pin<&mut Self>,
+            _cx: &mut Context<'_>,
+            buf: &[u8],
+        ) -> Poll<io::Result<usize>> {
+            assert_eq!(self.cnt, 0);
+            self.buf.extend(&buf[0..4]);
+            Ok(4).into()
+        }
+
+        fn poll_flush(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+            Ok(()).into()
+        }
+
+        fn poll_shutdown(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+            Ok(()).into()
+        }
+    }
+
+    let mut wr = Wr {
+        buf: BytesMut::with_capacity(64),
+        cnt: 0,
+    };
+
+    let n = assert_ok!(wr.write(b"hello world").await);
+    assert_eq!(n, 4);
+    assert_eq!(wr.buf, b"hell"[..]);
+}