From c8f7ba7495fe246395d13c2572f8300293abd194 Mon Sep 17 00:00:00 2001
From: Jonathan Johnson <jon@khonsulabs.com>
Date: Thu, 8 Aug 2024 14:03:09 -0700
Subject: [PATCH] Fixing/improving capacity test

---
 muse-channel/src/tests.rs | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/muse-channel/src/tests.rs b/muse-channel/src/tests.rs
index 62b8b3d..4cb194e 100644
--- a/muse-channel/src/tests.rs
+++ b/muse-channel/src/tests.rs
@@ -41,20 +41,29 @@ fn capacity() {
     let (in_sender, in_receiver) = bounded(1);
     let (out_sender, out_receiver) = bounded(1);
 
-    std::thread::spawn(move || {
+    let remote_thread = std::thread::spawn(move || {
         while let Some(RootedValue::Primitive(Primitive::Int(value))) = in_receiver.recv() {
             out_sender
                 .send(RootedValue::Primitive(Primitive::Int(value + 1)))
                 .unwrap();
         }
+        out_sender.send(RootedValue::NIL).unwrap();
     });
+    // First message will process fully and fill the out channel
     in_sender
         .send(RootedValue::Primitive(Primitive::Int(0)))
         .unwrap();
+    // Second message will be read from the in channel and cause the task to
+    // pause.
     in_sender
         .send(RootedValue::Primitive(Primitive::Int(1)))
         .unwrap();
-    match in_sender.try_send(RootedValue::Primitive(Primitive::Int(2))) {
+    // Third message fills the in channel.
+    in_sender
+        .send(RootedValue::Primitive(Primitive::Int(2)))
+        .unwrap();
+    // Finally, try_send should report a full error.
+    match in_sender.try_send(RootedValue::Primitive(Primitive::Int(3))) {
         Err(TrySendError::Full(_)) => {}
         other => unreachable!("unexpected try_send result: {other:?}"),
     }
@@ -63,7 +72,7 @@ fn capacity() {
         Some(RootedValue::Primitive(Primitive::Int(1)))
     );
     in_sender
-        .send(RootedValue::Primitive(Primitive::Int(2)))
+        .send(RootedValue::Primitive(Primitive::Int(3)))
         .unwrap();
     assert_eq!(
         out_receiver.recv(),
@@ -73,7 +82,11 @@ fn capacity() {
         out_receiver.recv(),
         Some(RootedValue::Primitive(Primitive::Int(3)))
     );
-    for i in 3..100 {
+    assert_eq!(
+        out_receiver.recv(),
+        Some(RootedValue::Primitive(Primitive::Int(4)))
+    );
+    for i in 4..100 {
         in_sender
             .send(RootedValue::Primitive(Primitive::Int(i)))
             .unwrap();
@@ -82,6 +95,11 @@ fn capacity() {
             Some(RootedValue::Primitive(Primitive::Int(i + 1)))
         );
     }
+    // Disconnect the channel.
+    drop(in_sender);
+    assert_eq!(out_receiver.recv(), Some(RootedValue::NIL));
+    assert_eq!(out_receiver.recv(), None);
+    remote_thread.join().unwrap();
 }
 
 #[test]