example: Add mocked io example (#677)

* example: Add mocked io example

* fix mock example

* Remove uniex bound for mock impl

examples/Cargo.toml

@@ -158,6 +158,11 @@ path = "src/compression/server.rs"
 name = "compression-client"
 path = "src/compression/client.rs"
 
+[[bin]]
+name = "mock"
+path = "src/mock/mock.rs"
+
+
 [dependencies]
 tonic = { path = "../tonic", features = ["tls"] }
 prost = "0.7"

examples/src/mock/mock.rs

@@ -0,0 +1,124 @@
+use std::convert::TryFrom;
+use tonic::{
+    transport::{Endpoint, Server, Uri},
+    Request, Response, Status,
+};
+use tower::service_fn;
+
+pub mod hello_world {
+    tonic::include_proto!("helloworld");
+}
+
+use hello_world::{
+    greeter_client::GreeterClient,
+    greeter_server::{Greeter, GreeterServer},
+    HelloReply, HelloRequest,
+};
+
+#[tokio::main]
+async fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let (client, server) = tokio::io::duplex(1024);
+
+    let greeter = MyGreeter::default();
+
+    tokio::spawn(async move {
+        Server::builder()
+            .add_service(GreeterServer::new(greeter))
+            .serve_with_incoming(futures::stream::iter(vec![Ok::<_, std::io::Error>(
+                mock::MockStream(server),
+            )]))
+            .await
+    });
+
+    // Move client to an option so we can _move_ the inner value
+    // on the first attempt to connect. All other attempts will fail.
+    let mut client = Some(client);
+    let channel = Endpoint::try_from("http://[::]:50051")?
+        .connect_with_connector(service_fn(move |_: Uri| {
+            let client = client.take().unwrap();
+
+            async move { Ok::<_, std::io::Error>(mock::MockStream(client)) }
+        }))
+        .await?;
+
+    let mut client = GreeterClient::new(channel);
+
+    let request = tonic::Request::new(HelloRequest {
+        name: "Tonic".into(),
+    });
+
+    let response = client.say_hello(request).await?;
+
+    println!("RESPONSE={:?}", response);
+
+    Ok(())
+}
+
+#[derive(Default)]
+pub struct MyGreeter {}
+
+#[tonic::async_trait]
+impl Greeter for MyGreeter {
+    async fn say_hello(
+        &self,
+        request: Request<HelloRequest>,
+    ) -> Result<Response<HelloReply>, Status> {
+        println!("Got a request: {:?}", request);
+
+        let reply = hello_world::HelloReply {
+            message: format!("Hello {}!", request.into_inner().name),
+        };
+        Ok(Response::new(reply))
+    }
+}
+
+mod mock {
+    use std::{
+        pin::Pin,
+        task::{Context, Poll},
+    };
+
+    use tokio::io::{AsyncRead, AsyncWrite, ReadBuf};
+    use tonic::transport::server::Connected;
+
+    #[derive(Debug)]
+    pub struct MockStream(pub tokio::io::DuplexStream);
+
+    impl Connected for MockStream {
+        type ConnectInfo = ();
+
+        /// Create type holding information about the connection.
+        fn connect_info(&self) -> Self::ConnectInfo {}
+    }
+
+    impl AsyncRead for MockStream {
+        fn poll_read(
+            mut self: Pin<&mut Self>,
+            cx: &mut Context<'_>,
+            buf: &mut ReadBuf<'_>,
+        ) -> Poll<std::io::Result<()>> {
+            Pin::new(&mut self.0).poll_read(cx, buf)
+        }
+    }
+
+    impl AsyncWrite for MockStream {
+        fn poll_write(
+            mut self: Pin<&mut Self>,
+            cx: &mut Context<'_>,
+            buf: &[u8],
+        ) -> Poll<std::io::Result<usize>> {
+            Pin::new(&mut self.0).poll_write(cx, buf)
+        }
+
+        fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<std::io::Result<()>> {
+            Pin::new(&mut self.0).poll_flush(cx)
+        }
+
+        fn poll_shutdown(
+            mut self: Pin<&mut Self>,
+            cx: &mut Context<'_>,
+        ) -> Poll<std::io::Result<()>> {
+            Pin::new(&mut self.0).poll_shutdown(cx)
+        }
+    }
+}

tests/compression/Cargo.toml

@@ -18,7 +18,7 @@ tower-http = { version = "0.1", features = ["map-response-body", "map-request-bo
 bytes = "1"
 futures = "0.3"
 pin-project = "1.0"
-hyper = "0.14"
+hyper = "0.14.3"
 
 [build-dependencies]
 tonic-build = { path = "../../tonic-build", features = ["compression"] }