diff -r 359884685eab -r 8403cc54bc83 tests/test-stdio.py
--- a/tests/test-stdio.py	Sun Jul 05 13:05:06 2020 +0200
+++ b/tests/test-stdio.py	Sun Jul 05 13:09:22 2020 +0200
@@ -100,6 +100,18 @@
             test_stdout_ptys_unbuffered
         )
 
+    def test_stderr_pipes(self):
+        self._test('stderr', _pipes, UNBUFFERED)
+
+    def test_stderr_ptys(self):
+        self._test('stderr', _ptys, UNBUFFERED)
+
+    def test_stderr_pipes_unbuffered(self):
+        self._test('stderr', _pipes, UNBUFFERED, python_args=['-u'])
+
+    def test_stderr_ptys_unbuffered(self):
+        self._test('stderr', _ptys, UNBUFFERED, python_args=['-u'])
+
 
 if __name__ == '__main__':
     import silenttestrunner