first_stage_test: Add test_closed_stderr

Signed-off-by: Marc Hartmayer <[email protected]>

Author: mhartmay

tests/first_stage_test.py

@@ -87,6 +87,18 @@ class DummyConnectionNonBlocking(mitogen.parent.Connection):
     name_prefix = "dummy_non_blocking"
 
 
+class DummyConnectionClosedStderr(mitogen.parent.Connection):
+    """Dummy closed stderr connection"""
+
+    pipe_size = 4096 if getattr(fcntl, "F_SETPIPE_SZ", None) else None
+    create_child = staticmethod(
+        functools.partial(
+            own_create_child, blocking=True, pipe_size=pipe_size, preexec_fn=lambda: os.close(2)
+        )
+    )
+    name_prefix = "dummy_closed_stderr"
+
+
 class ConnectionTest(testlib.RouterMixin, testlib.TestCase):
     def test_stdin_non_blocking(self):
         """Test that first stage works with non-blocking STDIN
@@ -126,6 +138,25 @@ def test_stdin_blocking(self):
         self.assertEqual(3, ctx.call(operator.add, 1, 2))
         logs = log.stop()
 
+    def test_stderr_closed(self):
+        """Test that first stage works with closed STDERR
+
+        The boot command should read the preamble from STDIN, write all ECO
+        markers to STDOUT, and then execute the preamble.
+
+        This test writes the complete preamble to blocking STDIN.
+
+        1. Fork child reads from blocking STDIN
+        2. Fork child writes all data as expected by the protocol.
+        3. A context call works as expected.
+
+        """
+        log = testlib.LogCapturer()
+        log.start()
+        ctx = self.router._connect(DummyConnectionClosedStderr, connect_timeout=0.5)
+        self.assertEqual(3, ctx.call(operator.add, 1, 2))
+        logs = log.stop()
+
 
 class CommandLineTest(testlib.RouterMixin, testlib.TestCase):
     # Ensure this version of Python produces a command line that is sufficient