Using [pytest-xprocess](https://pytest-xprocess.readthedocs.io/) proved
not being as useful as I thought at first, because it was causing
intermitent failures when starting the process.
The code now directly uses `subprocess.popen` calls to start the server.
The tests are grouped together using the following decorator:
`@pytest.mark.xdist_group(name="websockets")`
Tests now need to be run with the `pytest --dist loadgroup` so that all
tests of the same group happen on the same process.
More details on this blogpost:
https://blog.notmyidea.org/start-a-process-when-using-pytest-xdist.html
Because we are dealing with technologies using overlapping vocabulary,
it is easy to get lost. Hopefully this change makes it clear that it
converts geoJSON inputs in Leaflet / uMap objects.
It is now possible to create proxy objects using `sync_engine.proxy(object)`.
The returned proxy object will automatically inject `metadata` and
`subject` parameters, after looking for them in the `getSyncMetadata`
method (these are only known to the synced objects).
As a result, the calls are now simplified:
```
this.sync.update("key", "value")
```
This allows to handle the loading of the settings in a consistant way,
and aditionnaly to provide a way to override the `WEBSOCKET_BACK_HOST`
and `WEBSOCKET_BACK_PORT` settings with arg commands `--host` and
`--port`.
Without this change, because of how we are currently loading our
settings, we would require the settings the be exposed by the
`umap.settings.__init__` file.
Previous implementations were exposing these settings, with the
following code:
```python
settings_as_dict = {k: v for k, v in globals().items() if k.isupper()}
```
It is now using `WEBSOCKET_BACK_HOST`, `WEBSOCKET_BACK_PORT` and
`WEBSOCKET_FRONT_URI`.
We need to take in consideration that the "front" WebSocket address
(that clients will connect to) might be different than the "back" ip and
port which are bound in the host.
This happens for instance for reverse proxies, or when running inside
a container.
We considered using a `WEBSOCKET_TLS` setting, to try guessing the
"front" address based on `WEBSOCKET_HOST`, `WEBSOCKET_PORT` and
`WEBSOCKET_TLS`, but as the back and front address can differ, this
would need to introduce a `WEBSOCKET_URI` in any case, so we went with
just using it, and not adding an extra `WEBSOCKET_TLS`.
This allows the merge algorithm to not be lost when receiving changes.
Without this change, the optimistic merge algorithm isn't able to make
the distinction between peers, and features end up duplicated.
It's now it's responsability to get the authentication token from
the http server and pass it to the websocket server, it will make it
possible to redo the roundtrip when getting disconnected.
In some cases, you want to stop the propagation of events. The previous
code was using `fromSync=true` and `sync=false` interchangeably. This
makes it use `sync=false` everywhere.
