From 4591bff76a5f7f07dfd92d1215a55435413b8f39 Mon Sep 17 00:00:00 2001
From: Stefan Nikolei <stefan@nikolei.eu>
Date: Tue, 3 Sep 2024 20:45:13 +0200
Subject: [PATCH] add explicit test for null as encoding

---
 .../StreamWriter/StreamWriter.CtorTests.cs                | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/libraries/System.Runtime/tests/System.IO.Tests/StreamWriter/StreamWriter.CtorTests.cs b/src/libraries/System.Runtime/tests/System.IO.Tests/StreamWriter/StreamWriter.CtorTests.cs
index bf768cf9ff725b..bf0075139e699d 100644
--- a/src/libraries/System.Runtime/tests/System.IO.Tests/StreamWriter/StreamWriter.CtorTests.cs
+++ b/src/libraries/System.Runtime/tests/System.IO.Tests/StreamWriter/StreamWriter.CtorTests.cs
@@ -48,7 +48,13 @@ public static void UnicodeEncoding()
             TestEncoding(System.Text.Encoding.Unicode, "This is Unicode\u00FF");
         }
 
-        private static void TestEncoding(System.Text.Encoding encoding, string testString)
+        [Fact]
+        public static void NullEncoding()
+        {
+            TestEncoding(null, "This is UTF8\u00FF");
+        }
+
+        private static void TestEncoding(System.Text.Encoding? encoding, string testString)
         {
             StreamWriter sw2;
             StreamReader sr2;