From f155c5119b1f0ba74918edb6eb603489f80b5194 Mon Sep 17 00:00:00 2001
From: Uwe Reimann <uwe.reimann@phenetic.io>
Date: Fri, 2 Jun 2023 17:17:31 +0200
Subject: [PATCH] Add tests for mergePreferred

---
 .../src/test/scala/fs2/StreamMergeSuite.scala | 33 +++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/core/shared/src/test/scala/fs2/StreamMergeSuite.scala b/core/shared/src/test/scala/fs2/StreamMergeSuite.scala
index 6ff3b03a1b..282115c05a 100644
--- a/core/shared/src/test/scala/fs2/StreamMergeSuite.scala
+++ b/core/shared/src/test/scala/fs2/StreamMergeSuite.scala
@@ -242,4 +242,37 @@ class StreamMergeSuite extends Fs2Suite {
         }
     }
   }
+
+  test("mergePreferred prefers") {
+    forAllF { (leftStream: Stream[Pure, Int], rightStream: Stream[Pure, Int]) =>
+      val leftTagged = leftStream.covary[IO]
+      val rightTagged = rightStream.covary[IO].delayBy(10.milli)
+      leftTagged
+        .mergePreferred(rightTagged)
+        .assertEmitsSameAs(leftStream ++ rightStream)
+    }
+  }
+
+  test("mergePreferred fully consumes this") {
+    forAllF { (stream: Stream[Pure, Int]) =>
+      stream.covary[IO].mergePreferred(Stream.empty.covary[IO]).assertEmitsSameAs(stream)
+    }
+  }
+
+  test("mergePreferred fully consumes that") {
+    forAllF { (stream: Stream[Pure, Int]) =>
+      Stream.empty.covary[IO].mergePreferred(stream.covary[IO]).assertEmitsSameAs(stream)
+    }
+  }
+
+  test("mergePreferred fully consumes both") {
+    forAllF { (leftStream: Stream[Pure, Int], rightStream: Stream[Pure, Int]) =>
+      val leftTagged = leftStream.covary[IO]
+      val rightTagged = rightStream.covary[IO]
+      leftTagged
+        .mergePreferred(rightTagged)
+        .assertEmitsUnorderedSameAs(leftStream ++ rightStream)
+    }
+  }
+
 }