Fixes # 415 - Close stdin when tearing down subprocesses in system-te…

…sts to prevent fd leaks

tests/system_test.py

@@ -372,6 +372,10 @@ def error(msg):
         # at this point the process has terminated, either of its own accord or
         # due to the above terminate call.
 
+        # prevent leak of stdin fd
+        if self.stdin:
+            self.stdin.close()
+
         if state is None and self.expect != Process.RUNNING:
             error("process was unexpectedly still running")
 
@@ -563,6 +567,13 @@ def __init__(self, name=None, config=Config(), pyinclude=None, wait=True,
         if wait:
             self.wait_ready()
 
+    def __enter__(self):
+        """Allows using the class in the `with` contextmanager"""
+        return self
+
+    def __exit__(self, *_):
+        self.teardown()
+
     @property
     def management(self):
         """Return a management agent proxy for this router"""

tests/system_tests_one_router.py

@@ -411,8 +411,8 @@ def test_01_listen_error(self):
         config = Qdrouterd.Config([
             ('router', {'mode': 'standalone', 'id': 'bad'}),
             ('listener', {'port': OneRouterTest.listen_port})])
-        r = Qdrouterd(name="expect_fail", config=config, wait=False)
-        self.assertEqual(1, r.wait())
+        with Qdrouterd(name="expect_fail", config=config, wait=False, expect=Process.EXIT_FAIL) as r:
+            self.assertEqual(1, r.wait())
 
     def test_02_pre_settled(self):
         addr = self.address + '/closest/' + str(OneRouterTest.closest_count)