tests: Setup automated tests with pytest

[MattHag]

Related #1097

[pfps]

This PR just adds a testing harness, right?

The reason I ask is that a Solaar release will go out soon. If this PR doesn't affect Solaar then it can be part of the release.

[pfps]

@MattHag
I'm not sure what failed in the tests. Can you take a look?

[MattHag]

I'll take a look. Yes, it only adds support for automated tests and as side effect tests, that the package can be installed.

[pfps]

@MattHag Does this PR also allow running the tests locally?

[MattHag]

Yeah, sure.

1. Install the package with test dependencies pip install -e .[test] to get pytest and
2. use the command pytest to run all tests at once.

[pfps]

@MattHag Tests work locally.

[pfps]

@MattHag I wrote my first test - and found a bug!

[MattHag]

The reason for the given error is a missing dbus dependency, that is not pre-installed in the Ubuntu base image.

I'll follow the installation page and add necessary dependencies.
https://pwr-solaar.github.io/Solaar/installation

[pfps]

Yeah, that's a problem with installing Solaar. It depends on quite a few packages and some distributions don't have them installed by default.

[MattHag]

We can (later) add a Makefile with targets for the different installations, depending on distribution and operating system. This simplifies the local setup and GitHub CI can leverage the same install procedure.

OS dependencies

For GitHub and local Ubuntu installations, you could then use the same command, e.g.
make install ubuntu
or even try to detect the OS and use a simple make install command.

Python dependencies

The pip dependencies can be installed with pip automatically. The default install would be
pip install .
and could replace all the python dependency paragraph, which requires maintenance.

[MattHag]

With just two additional dependencies, it works on Ubuntu 22.04, which is used in our GitHub CI.
sudo install libdbus-1-dev libglib2.0-dev

[pfps]

Looks good now