Update docs on using the library fingerprints in HA (#599)

* Update fingerprints_in_homeassistant.rst

* Update fingerprints_in_homeassistant.rst

* Update fingerprints_in_homeassistant.rst

docs/source/development/fingerprints_in_homeassistant.rst

@@ -1,52 +1,29 @@
 Using fingerprints in Home Assistant
 ====================================
-Sometimes it can be useful to load the **fingerprints** used for our **pytest suite** in the development of the Home Assistant component. 
+Sometimes it can be useful to load the **fingerprints** used for our **pytest suite** in the development of the Home Assistant component.
+This enables debugging of the UI in Home Assistant which is not possible from pytest alone.
 
-Set up bimmer_connected
------------------------
-Clone the repository to ``~/bimmer_connected``:
-
-.. code-block:: bash
+.. warning::
+  This is for the `Home Assistant development environment <https://developers.home-assistant.io/docs/development_environment>`_ only! Do not do this on your live instance!
 
-   git clone https://github.com/bimmerconnected/bimmer_connected.git ~/bimmer_connected
+Setup and start Home Assistant in the `development environment <https://developers.home-assistant.io/docs/development_environment>`_ at least once and let all python packages install (``hass -c ./config``).
+If not already done, set up the **BMW Connected Drive Integration**. You need to login a MyBMW account at least once. Shut down Homeassistant afterwards.
 
 .. note::
-
-  Make sure that you can access this path from inside your Home Assistant virtual environment!
-
-Edit the  ``_get_vehicles()`` function in `account.py#L370-L392 <https://github.com/bimmerconnected/bimmer_connected/blob/master/bimmer_connected/account.py#L370-L392>`_
-and add the following code between ``self._get_oauth_token()`` and ``for brand in CarBrand:``:
-
-.. code-block:: python
-
-   from pathlib import Path
-   files = (Path().home() / "bimmer_connected" / "test" / "responses").rglob("vehicles_v2_*_0.json")
-   for file in files:
-     for vehicle_dict in json.load(open(file, 'r')):
-       # If vehicle already exists, just update it's state
-       existing_vehicle = self.get_vehicle(vehicle_dict["vin"])
-       if existing_vehicle:
-         existing_vehicle.update_state(vehicle_dict)
-       else:
-         self._vehicles.append(MyBMWVehicle(self, vehicle_dict))
+  The MyBMW account does not need to contain vehicles, a demo account without attached vehicles is sufficient.
 
-Set up Home Assistant
----------------------
-If not already done, `set up the Home Assistant development environment <https://developers.home-assistant.io/docs/development_environment>`_.
+Now, we have to "hack" our mocked backend calls into Home Assistant.
 
-Now start Home Assistant at least once and let all python packages install (``hass -c ./config``). 
-If not already done, set up the **BMW Connected Drive Integration** in Home Assistant. 
-Shut down Homeassistant afterwards.
+Edit ``homeassistant/components/bmw_connected_drive/coordinator.py`` and locate the function ``def _async_update_data()``. We now have to replace ``await self.account.get_vehicles()``. The ``try .. except`` block should look like this:
 
-In the Home Assistant virtual environment, install the freshly adjusted version of ``bimmer_connected``:
-
-.. code-block:: bash
-
-  pip3 install -e ~/bimmer_connected
-
-Start Home Assistant using ``hass -c ./config --skip-pip`` and see all cars we have fingerprints of + your own cars.
+.. code-block:: python
 
-.. warning::
-   If ``--skip-pip`` is omitted when starting Home Assistant, the version of ``bimmer_connected`` defined in 
-   ``homeassistant/components/bmw_connected_drive/manifest.json`` will be loaded and the Home Assistant last two steps have to be executed again.
+  ...
+          try:
+              from bimmer_connected.tests.conftest import MyBMWMockRouter, ALL_STATES, ALL_CHARGING_SETTINGS
+              with MyBMWMockRouter(["WBY00000000REXI01"], ALL_STATES, ALL_CHARGING_SETTINGS):
+                  await self.account.get_vehicles()
+          except:
+  ...
 
+As the first parameter, you can specify a list of VINs for debugging or leave it empty (``None`` or ``[]``) to load all vehicles of our test suite.