wasi: Test multiple pollables of the same stream

crates/test-programs/src/bin/piped_multiple.rs

@@ -0,0 +1,34 @@
+use test_programs::wasi::cli::{stdin, stdout};
+
+fn main() {
+    match std::env::var("PIPED_SIDE")
+        .expect("piped tests require the PIPED_SIDE env var")
+        .as_str()
+    {
+        "PRODUCER" => producer(),
+        "CONSUMER" => consumer(),
+        side => panic!("unknown piped test side: {side}"),
+    }
+}
+
+const CHUNK: &[u8] = &[b'a'; 50];
+
+fn producer() {
+    let out = stdout::get_stdout();
+    let n = out.check_write().unwrap() as usize;
+    assert!(n > CHUNK.len());
+    out.write(CHUNK).unwrap();
+}
+
+fn consumer() {
+    let stdin = stdin::get_stdin();
+    let stdin_pollable1 = stdin.subscribe();
+    let stdin_pollable2 = stdin.subscribe();
+
+    // The two pollables are subscribed to the same resource, and must report the same readyness
+    stdin_pollable1.block();
+    assert!(stdin_pollable1.ready() && stdin_pollable2.ready());
+
+    let bytes = stdin.read(CHUNK.len() as u64).unwrap();
+    assert_eq!(&bytes, CHUNK);
+}

tests/all/piped_tests.rs

@@ -2,34 +2,26 @@
 
 use super::cli_tests::get_wasmtime_command;
 use anyhow::Result;
-use std::process::{ChildStdout, Command, Stdio};
+use std::process::Stdio;
 
-fn producer_command(component_path: &str) -> Result<Command> {
-    let mut cmd = get_wasmtime_command()?;
-    cmd.arg("run")
+pub fn run_wasmtime_piped(component_path: &str) -> Result<()> {
+    let mut producer = get_wasmtime_command()?
+        .arg("run")
         .arg("-Wcomponent-model")
         .arg("--env")
         .arg("PIPED_SIDE=PRODUCER")
         .arg(component_path)
-        .stdout(Stdio::piped());
-    Ok(cmd)
-}
+        .stdout(Stdio::piped())
+        .spawn()?;
 
-fn consumer_command(component_path: &str, input: ChildStdout) -> Result<Command> {
-    let mut cmd = get_wasmtime_command()?;
-    cmd.arg("run")
+    let mut consumer = get_wasmtime_command()?
+        .arg("run")
         .arg("-Wcomponent-model")
         .arg("--env")
         .arg("PIPED_SIDE=CONSUMER")
         .arg(component_path)
-        .stdin(input);
-    Ok(cmd)
-}
-
-pub fn run_wasmtime_piped(component_path: &str) -> Result<()> {
-    let mut producer = producer_command(component_path)?.spawn()?;
-    let stdout = producer.stdout.take().unwrap();
-    let mut consumer = consumer_command(component_path, stdout)?.spawn()?;
+        .stdin(producer.stdout.take().unwrap())
+        .spawn()?;
 
     let producer = producer.wait()?;
     if !producer.success() {
@@ -65,6 +57,11 @@ mod test_programs {
         run_wasmtime_piped(PIPED_SIMPLE_COMPONENT).unwrap()
     }
 
+    #[test]
+    fn piped_multiple() {
+        run_wasmtime_piped(PIPED_MULTIPLE_COMPONENT).unwrap()
+    }
+
     #[test]
     fn piped_polling() {
         run_wasmtime_piped(PIPED_POLLING_COMPONENT).unwrap()