tests: alter integration tests for stdio to not use a handrolled cat implementation

tests-integration/Cargo.toml

@@ -7,6 +7,7 @@ publish = false
 
 [[bin]]
 name = "test-cat"
+required-features = ["rt-process-io-util"]
 
 [[bin]]
 name = "test-mem"
@@ -17,6 +18,7 @@ name = "test-process-signal"
 required-features = ["rt-process-signal"]
 
 [features]
+rt-process-io-util = ["tokio/rt", "tokio/macros", "tokio/process", "tokio/io-util", "tokio/io-std"]
 # For mem check
 rt-net = ["tokio/rt", "tokio/rt-multi-thread", "tokio/net"]
 # For test-process-signal

tests-integration/src/bin/test-cat.rs

@@ -1,20 +1,14 @@
 //! A cat-like utility that can be used as a subprocess to test I/O
 //! stream communication.
 
-use std::io;
-use std::io::Write;
+use tokio::io::AsyncWriteExt;
 
-fn main() {
-    let stdin = io::stdin();
-    let mut stdout = io::stdout();
-    let mut line = String::new();
-    loop {
-        line.clear();
-        stdin.read_line(&mut line).unwrap();
-        if line.is_empty() {
-            break;
-        }
-        stdout.write_all(line.as_bytes()).unwrap();
-    }
-    stdout.flush().unwrap();
+#[tokio::main(flavor = "current_thread")]
+async fn main() {
+    let mut stdin = tokio::io::stdin();
+    let mut stdout = tokio::io::stdout();
+
+    tokio::io::copy(&mut stdin, &mut stdout).await.unwrap();
+
+    stdout.flush().await.unwrap();
 }

tests-integration/tests/process_stdio.rs

@@ -8,12 +8,22 @@ use tokio_test::assert_ok;
 
 use futures::future::{self, FutureExt};
 use std::convert::TryInto;
-use std::env;
 use std::io;
 use std::process::{ExitStatus, Stdio};
 
+// so, we need to change this back as a test, but for now this doesn't work because of:
+// https://github.com/rust-lang/rust/pull/95469
+//
+// undo when this is closed: https://github.com/tokio-rs/tokio/issues/4802
+
+// fn cat() -> Command {
+//     let mut cmd = Command::new(std::env!("CARGO_BIN_EXE_test-cat"));
+//     cmd.stdin(Stdio::piped()).stdout(Stdio::piped());
+//     cmd
+// }
+
 fn cat() -> Command {
-    let mut cmd = Command::new(env!("CARGO_BIN_EXE_test-cat"));
+    let mut cmd = Command::new("cat");
     cmd.stdin(Stdio::piped()).stdout(Stdio::piped());
     cmd
 }