1 files changed, 16 insertions, 0 deletions
diff --git a/test/ruby/test_io_m17n.rb b/test/ruby/test_io_m17n.rb
index 97512f0d61..734b0172ac 100644
--- a/test/ruby/test_io_m17n.rb
+++ b/test/ruby/test_io_m17n.rb
@@ -2547,4 +2547,20 @@ EOT
       end
     }
   end if /mswin|mingw/ =~ RUBY_PLATFORM
+
+  def test_read_with_buf_broken_ascii_only
+    a, b = IO.pipe
+    a.binmode
+    b.binmode
+    b.write("\xE2\x9C\x93")
+    b.close
+
+    buf = "".force_encoding("binary")
+    assert buf.ascii_only?, "should have been ascii_only?"
+    a.read(1, buf)
+    assert !buf.ascii_only?, "should not have been ascii_only?"
+  ensure
+    a.close rescue nil
+    b.close rescue nil
+  end
 end