feat: support setting the pythonpath in configuration YAMLs

[rpoisel]

Description

The pythonpath key allows specifying additional directories to be added to the Python search path (sys.path). This is particularly useful for including directories that contain Python modules and packages which are not installed in the standard library or not in the current directory.

Relative paths are resolved relative to the configuration file's location.

Specifying this option enables the environment to locate and import modules that are not in the default Python path.

Checklist

• Documentation for the feature
• Tests for the feature
• The arguments and description in doc/configuration.rst have been updated
• Add a section on how to use the feature to doc/usage.rst
• Add a section on how to use the feature to doc/development.rst
• PR has been tested
• Man pages have been regenerated

[Emantor]

Isn't this covered by the imports property already?

[rpoisel]

Isn't this covered by the imports property already?

My use-case was to load modules and packages from relative paths or non-standard locations. In my situation, I want to use shared code that has been added to my projects as git submodules.

Making these modules/packages available could also be done by setting the PYTHONPATH environment variable somewhere in the context of any labgrid-using python code. However, I wanted to make this part of the configuration, thus I introduced the pythonpath property.

Could you please have a look into the integration tests of this functionality?

• test_env_pythonpath_yaml_module
• test_env_pythonpath_yaml_package

[rpoisel]

The pythonpath property is, in my opinion, similar to the pythonpath configuration option in pytest. You can find more details here: pytest pythonpath.

By setting this variable, tools like labgrid-client will also search the specified paths for imported modules and packages.

[Emantor]

I am not convinced we should support two different mechanics for module imports. The imports functionality is narrower in scope and IMO suites the use case for in test case strategies quite well. The user can still set the PYTHONPATH explicitly outside of labgrid to make other modules available. @jluebbe, @Bastian-Krause whats your opinion on this?