1 files changed, 6 insertions, 0 deletions
diff --git a/test/ruby/test_io_m17n.rb b/test/ruby/test_io_m17n.rb
index 976aae8c2e..4d1a62381b 100644
--- a/test/ruby/test_io_m17n.rb
+++ b/test/ruby/test_io_m17n.rb
@@ -558,6 +558,12 @@ EOT
       assert_equal(eucjp, r.read)
     }
 
+    with_pipe("UTF-8") {|r,w|
+      w << "a" * 1023 + "\u3042" + "a" * 1022
+      w.close
+      assert_equal(true, r.read.valid_encoding?)
+    }
+
     with_pipe("UTF-8:EUC-JP") {|r,w|
       assert_equal(Encoding::UTF_8, r.external_encoding)
       assert_equal(Encoding::EUC_JP, r.internal_encoding)