L2SS-594: Use process=True for the DeviceTestContext to avoid crashes, and...

L2SS-594: Use process=True for the DeviceTestContext to avoid crashes, and move test code into the Device to fix the test.

tangostationcontrol/tangostationcontrol/test/common/test_lofar_logging.py

@@ -74,25 +74,36 @@ class TestLofarLogging(base.TestCase):
 
         logger = lofar_logging.configure_logger()
 
+        # alias to distinguish from other "self"s
+        test_object = self
+
+        # Since we spawn a new process for the Device ("process=True" in the DeviceTestContext),
+        # and the mock doesn't work across processes, we do all of our mocking and checks in
+        # the device itself. If any Exception is raised, it will be marshalled to the device
+        # server by Tango and reraised here in the test as a DevFailed exception.
+
         # create a Tango Device that logs something
         class MyDevice(Device):
             def init_device(self):
-                self.log_deeper_in_stack()
+                with mock.patch.object(device_server.DeviceImpl, '__info_stream') as m_info_stream:
+                    self.log_deeper_in_stack()
 
-            def log_deeper_in_stack(self):
-                logger.info("test")
+                    # check if we actually routed the log to self.info_stream
+                    test_object.assertEqual(1, m_info_stream.call_count, msg="configure_logger did not send logs to active Tango device")
 
-        with mock.patch.object(device_server.DeviceImpl, '__info_stream') as m_info_stream:
-            with DeviceTestContext(MyDevice) as mydevice:
-                self.assertEqual(1, m_info_stream.call_count, msg="configure_logger did not send logs to active Tango device")
+                    # Lookup our "test" logline among f.e. the debug messages output by Tango
+                    test_record = [record for record in test_object.memory_handler.records if record.msg == "test log_deeper_in_stack"]
 
-                # Lookup our "test" logline among f.e. the debug messages output by Tango
-                test_record = [record for record in self.memory_handler.records if record.msg == "test"]
+                    # Tango uses slightly different class representations of MyDevice, so
+                    # we can't compare them direclty. Just verify we're talking about the same thing.
+                    test_object.assertEqual(str(self), str(test_record[0].tango_device), msg="configure_logging did not detect active Tango device")
 
-                # Tango uses slightly different class representations of MyDevice, so
-                # we can't compare them direclty. Just verify we're talking about the same thing.
-                self.assertEqual(str(mydevice), str(test_record[0].tango_device), msg="configure_logging did not detect active Tango device")
+            def log_deeper_in_stack(self):
+                logger.info("test log_deeper_in_stack")
 
+        # if init_device fails, an exception will be thrown
+        with DeviceTestContext(MyDevice, process=True) as mydevice:
+            pass
 
     def test_log_exceptions(self):
         """ Test whether log_exceptions actually logs and reraises exceptions. """