Disconnecting from the printer before when turning its relay off (#207)

* Draft: disconnecting from the printer before when turning its relay off.

* Fixing the tests.

* Testing is_printer_relay() method.

* Testing toggle_relay() method for the case of printer relay.

* Update tests/test_init.py

* Handling the case of double turned on the printer relay.

octoprint_octorelay/__init__.py

@@ -171,8 +171,9 @@ def on_event(self, event, payload):
             self.handle_plugin_event(PRINTING_STOPPED)
         elif hasattr(Events, "CONNECTIONS_AUTOREFRESHED"): # Requires OctoPrint 1.9+
             if event == Events.CONNECTIONS_AUTOREFRESHED:
-                self._logger.debug("Connecting to the printer")
-                self._printer.connect()
+                if payload is not None and "ports" in payload and len(payload["ports"]) > 0:
+                    self._logger.debug("Connecting to the printer")
+                    self._printer.connect()
         #elif event == Events.PRINT_CANCELLING:
             # self.print_stopped()
         #elif event == Events.PRINT_CANCELLED:
@@ -209,11 +210,20 @@ def handle_plugin_event(self, event, scope = None):
         if needs_ui_update:
             self.update_ui() # issue 190
 
+    def is_printer_relay(self, index) -> bool:
+        printer_relay = self._settings.get(["common", "printer"], merged=True) # expensive
+        return printer_relay is not None and printer_relay == index
+
     def toggle_relay(self, index, target: Optional[bool] = None):
         settings = self._settings.get([index], merged=True) # expensive
         if not bool(settings["active"]):
             self._logger.debug(f"Refusing to switch the relay {index} since it's disabled")
             return
+        if target is not True and self.is_printer_relay(index):
+            self._logger.debug(f"{index} is the printer relay")
+            if self._printer.is_operational():
+                self._logger.debug(f"Disconnecting from the printer before turning {index} OFF")
+                self._printer.disconnect()
         pin = int(settings["relay_pin"] or 0)
         inverted = bool(settings["inverted_output"])
         relay = Relay(pin, inverted)

tests/test_init.py

@@ -505,9 +505,22 @@ def test_update_ui(self):
                 "MockedIdentifier", expected_model
             )
 
+    def test_is_printer_relay(self):
+        # Should assert the equality of the common/printer value with the supplied argument
+        cases = [
+            { "printer": "r4", "expected": True },
+            { "printer": "r5", "expected": False },
+            { "printer": None, "expected": False }
+        ]
+        for case in cases:
+            self.plugin_instance._settings.get = Mock(return_value=case["printer"])
+            actual = self.plugin_instance.is_printer_relay("r4")
+            self.assertEqual(actual, case["expected"])
+
     @patch("os.system")
     def test_toggle_relay(self, system_mock):
         # Should toggle the relay and execute a command matching its new state
+        self.plugin_instance.is_printer_relay = Mock(return_value=False)
         cases = [
             { "target": True, "inverted": False, "expectedCommand": "CommandON" },
             { "target": True, "inverted": True, "expectedCommand": "CommandON" },
@@ -551,6 +564,33 @@ def test_toggle_relay__disabled(self):
         self.plugin_instance.toggle_relay("r4", True)
         relayMock.toggle.assert_not_called()
 
+    def test_toggle_relay__printer(self):
+        # Should disconnect from the printer when turning its relay off
+        cases = [
+            { "target": None, "is_printer": True, "is_operational": True },
+            { "target": False, "is_printer": True, "is_operational": True },
+            { "target": True, "is_printer": True, "is_operational": True },
+            { "target": False, "is_printer": True, "is_operational": False },
+            { "target": False, "is_printer": False, "is_operational": True },
+        ]
+        self.plugin_instance._settings.get = Mock(return_value={
+            "active": True,
+            "relay_pin": 17,
+            "inverted_output": False,
+            "cmd_on": None,
+            "cmd_off": None
+        })
+        relayMock.toggle = Mock(return_value=False)
+        for case in cases:
+            self.plugin_instance._printer.reset_mock()
+            self.plugin_instance.is_printer_relay = Mock(return_value=case["is_printer"])
+            self.plugin_instance._printer.is_operational = Mock(return_value=case["is_operational"])
+            self.plugin_instance.toggle_relay("r4", case["target"])
+            if case["target"] is not True and case["is_printer"] and case["is_operational"]:
+                self.plugin_instance._printer.disconnect.assert_called_with()
+            else:
+                self.plugin_instance._printer.disconnect.assert_not_called()
+
     @patch("octoprint.plugin")
     def test_on_settings_save(self, plugins_mock):
         # Should call the SettingsPlugin event handler with own instance and supplied argument
@@ -568,33 +608,38 @@ def test_on_event(self):
         cases = [
             {
                 "event": Events.CLIENT_OPENED,
+                "payload": {"remoteAddress": "127.0.0.1"},
                 "expectedMethod": self.plugin_instance.update_ui,
                 "expectedParams": []
             },
             {
                 "event": Events.PRINT_STARTED,
+                "payload": {"name": "test.gcode"},
                 "expectedMethod": self.plugin_instance.handle_plugin_event,
                 "expectedParams": ["PRINTING_STARTED"]
             },
             {
                 "event": Events.PRINT_DONE,
+                "payload": {"name": "test.gcode"},
                 "expectedMethod": self.plugin_instance.handle_plugin_event,
                 "expectedParams": ["PRINTING_STOPPED"]
             },
             {
                 "event": Events.PRINT_FAILED,
+                "payload": {"name": "test.gcode"},
                 "expectedMethod": self.plugin_instance.handle_plugin_event,
                 "expectedParams": ["PRINTING_STOPPED"]
             },
         ]
         if hasattr(Events, "CONNECTIONS_AUTOREFRESHED"): # Requires OctoPrint 1.9+
             cases.append({
                 "event": Events.CONNECTIONS_AUTOREFRESHED,
+                "payload": {"ports": ["/dev/ttyUSB0"]},
                 "expectedMethod": self.plugin_instance._printer.connect,
                 "expectedParams": []
             })
         for case in cases:
-            self.plugin_instance.on_event(case["event"], "MockedPayload")
+            self.plugin_instance.on_event(case["event"], case["payload"])
             case["expectedMethod"].assert_called_with(*case["expectedParams"])
 
     def test_on_after_startup(self):
@@ -814,6 +859,7 @@ def test_handle_get_status_command(self, jsonify_mock):
     def test_handle_update_command(self, system_mock, jsonify_mock):
         # Should toggle the relay state, execute command and update UI when having permission
         self.plugin_instance.update_ui = Mock()
+        self.plugin_instance.is_printer_relay = Mock(return_value=False)
         cases = [
             {
                 "index": "r4",