[2781] modify mock classes in test_utils.py

add check_command_without_recvmsg() into MyModuleCCSession and add default
values into args of __group_recvmsg(). These changes are for referring and
executing from the unit tests.

src/bin/stats/tests/test_utils.py

@@ -311,6 +311,8 @@ class MyModuleCCSession(isc.config.ConfigData):
         self.stopped = False
         self.closed = False
         self.lname = 'mock_mod_ccs'
+        self._msg = None
+        self._env = None
 
     def start(self):
         pass
@@ -321,6 +323,10 @@ class MyModuleCCSession(isc.config.ConfigData):
     def close(self):
         self.closed = True
 
+    def check_command_without_recvmsg(self, msg, env):
+        self._msg = msg
+        self._env = env
+
 class MyStats(stats.Stats):
     """A faked Stats class for unit tests.
 
@@ -411,7 +417,7 @@ class MyStats(stats.Stats):
         self._seq += 1
         return self._seq
 
-    def __group_recvmsg(self, nonblocking, seq):
+    def __group_recvmsg(self, nonblocking = True, seq = None):
         """Faked ModuleCCSession.group_recvmsg for tests.
 
         Skipping actual network communication, and returning an internally