Fix slow OBD value load on dashboard (BUG-19)

tests/test_app_obd.py

@@ -72,5 +72,59 @@ class ClearDtcCodesTest(unittest.TestCase):
         mock_mark.assert_called_once()
 
 
+class EmitCurrentStateTest(unittest.TestCase):
+    def setUp(self):
+        self._saved = {
+            name: getattr(app_obd, name)
+            for name in (
+                "speed", "rpm", "coolant_temp", "fuel_level",
+                "throttle_position", "mil_on", "dtc_codes",
+            )
+        }
+
+    def tearDown(self):
+        for name, value in self._saved.items():
+            setattr(app_obd, name, value)
+
+    def _emitted(self, mock_emit):
+        return {call.args[0]: call.args[1] for call in mock_emit.call_args_list}
+
+    def test_connected_emits_current_values(self):
+        app_obd.speed = 42.5
+        app_obd.rpm = 1200
+        app_obd.coolant_temp = 88.0
+        app_obd.fuel_level = 60.0
+        app_obd.throttle_position = 12.0
+        app_obd.mil_on = False
+        app_obd.dtc_codes = []
+        with patch.object(app_obd, "_is_car_connected", return_value=True), \
+             patch("modules.app_events.socketio.emit") as mock_emit:
+            app_obd.emit_current_state()
+        emitted = self._emitted(mock_emit)
+        self.assertEqual(emitted["obd_status"], "Connected")
+        self.assertEqual(emitted["obd_rpm"], 1200)
+        self.assertEqual(emitted["obd_coolant_temp"], 88.0)
+        self.assertEqual(emitted["obd_fuel_level"], 60.0)
+        self.assertEqual(emitted["obd_throttle"], 12.0)
+        # speed is emitted as [time, speed]
+        self.assertEqual(emitted["obd_speed"][1], 42.5)
+
+    def test_disconnected_emits_dashes(self):
+        app_obd.rpm = None
+        app_obd.coolant_temp = None
+        app_obd.fuel_level = None
+        app_obd.throttle_position = None
+        with patch.object(app_obd, "_is_car_connected", return_value=False), \
+             patch("modules.app_events.socketio.emit") as mock_emit:
+            app_obd.emit_current_state()
+        emitted = self._emitted(mock_emit)
+        self.assertEqual(emitted["obd_status"], "Disconnected")
+        self.assertEqual(emitted["obd_speed"], "-")
+        self.assertEqual(emitted["obd_rpm"], "-")
+        self.assertEqual(emitted["obd_coolant_temp"], "-")
+        self.assertEqual(emitted["obd_fuel_level"], "-")
+        self.assertEqual(emitted["obd_throttle"], "-")
+
+
 if __name__ == "__main__":
     unittest.main()