What's the problem this feature will solve?

pytest seems designed to test Python packages.
However, it's getting used to test applications as well.
The main problem with testing applications is telling pytest how to find the code under test.
Specifically, sys.path needs modified to include the directory where the code under test lives.

Describe the solution you'd like

I'd like a srcpaths setting. We already have testpaths.
srcpaths would be a list of directories to add to sys.path.

Any project that isn't an installable package (installable through pip) that wants the source code and test code in different directories needs this.

Alternative Solutions

• Roll your own solutions
• Plugins
  • pytest-srcpaths does just this thing.
  • pytest-pythonpaths does more
    • does this
    • also has a site_dirs feature which I still don't understand
    • also (undocumented) adds the current directory to sys.path

Additional context