Delay debug channel messages

Author: unstubbable

fixtures/flight/src/index.js

@@ -14,6 +14,40 @@ function findSourceMapURL(fileName) {
   );
 }
 
+function createDelayedStream(
+  stream: ReadableStream<Uint8Array>
+): ReadableStream<Uint8Array> {
+  return new ReadableStream({
+    async start(controller) {
+      const reader = stream.getReader();
+
+      try {
+        while (true) {
+          const {done, value} = await reader.read();
+          if (done) {
+            if (!controller.desiredSize === null) {
+              controller.close();
+            }
+            break;
+          } else {
+            // Artificially delay between enqueuing chunks.
+            await new Promise(resolve => setTimeout(resolve, 10));
+            if (controller.desiredSize !== null) {
+              controller.enqueue(value);
+            }
+          }
+        }
+      } catch (error) {
+        if (controller.desiredSize !== null) {
+          controller.error(error);
+        }
+      } finally {
+        reader.releaseLock();
+      }
+    },
+  });
+}
+
 async function createWebSocketStream(url) {
   const ws = new WebSocket(url);
   ws.binaryType = 'arraybuffer';
@@ -49,7 +83,7 @@ async function createWebSocketStream(url) {
     },
   });
 
-  return {readable, writable};
+  return {readable: createDelayedStream(readable), writable};
 }
 
 let updateRoot;