From 8a211768dd1475118a9a646e1307b48a4ace1f8c Mon Sep 17 00:00:00 2001
From: Ankit Kumar <ankitkumarrain12@gmail.com>
Date: Tue, 17 Mar 2026 14:30:43 +0000
Subject: [PATCH] Wrote test and fixed the bug for confalte chunk

---
 core/shared/src/main/scala/fs2/Stream.scala   |  2 +-
 .../test/scala/fs2/StreamConflateSuite.scala  | 20 +++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/core/shared/src/main/scala/fs2/Stream.scala b/core/shared/src/main/scala/fs2/Stream.scala
index a3642794a8..2e92d47cf8 100644
--- a/core/shared/src/main/scala/fs2/Stream.scala
+++ b/core/shared/src/main/scala/fs2/Stream.scala
@@ -576,7 +576,7 @@ final class Stream[+F[_], +O] private[fs2] (private[fs2] val underlying: Pull[F,
     * The `chunkLimit` parameter controls backpressure on the source stream.
     */
   def conflateChunks[F2[x] >: F[x]: Concurrent](chunkLimit: Int): Stream[F2, Chunk[O]] =
-    Stream.eval(Channel.bounded[F2, Chunk[O]](chunkLimit)).flatMap { chan =>
+    Stream.eval(Channel.bounded[F2, Chunk[O]](chunkLimit - 1)).flatMap { chan =>
       val producer = chunks.through(chan.sendAll)
       val consumer = chan.stream.chunks.map(_.combineAll)
       consumer.concurrently(producer)
diff --git a/core/shared/src/test/scala/fs2/StreamConflateSuite.scala b/core/shared/src/test/scala/fs2/StreamConflateSuite.scala
index c50b7c4451..cd7c9d9b84 100644
--- a/core/shared/src/test/scala/fs2/StreamConflateSuite.scala
+++ b/core/shared/src/test/scala/fs2/StreamConflateSuite.scala
@@ -23,6 +23,7 @@ package fs2
 
 import cats.effect.IO
 import cats.effect.testkit.TestControl
+import cats.syntax.all._
 
 import scala.concurrent.duration._
 
@@ -44,4 +45,23 @@ class StreamConflateSuite extends Fs2Suite {
         )
     )
   }
+  test("conflateChunks respects chunk limit") {
+
+    (1 to 1000).toList.traverse_ { _ =>
+      Stream(1, 2, 3, 4, 5, 6, 7)
+        .covary[IO]
+        .chunkLimit(1)
+        .unchunks
+        .conflateChunks(3)
+        .compile
+        .toList
+        .map { chunks =>
+          assert(
+            chunks.forall(_.size <= 3),
+            s"Expected all chunks <= 3, but got: $chunks"
+          )
+        }
+    }
+  }
+
 }