LSP library search path does not match Robot Framework

[osrjv]

Describe the bug
Robot Framework searches relative library imports based on sys.path as a fallback. LSP only searches relative to the working directory. As a result, certain imports work while running robots, but fail when creating libspec for LSP.

RF implementation visible here: https://github.com/robotframework/robotframework/blob/f45747dfec1095359379ba0088cecd955a83e576/src/robot/utils/robotpath.py#L157

Originally reported on forums: https://forum.robocorp.com/t/vscode-new-create-robot-project-cant-find-python-keywords/589

To Reproduce
Steps to reproduce the behavior:

1. Create Extended template with Robocorp Lab (or rcc), try to open tasks.robot with LSP

or

1. Create the following structure:

libraries/Library.py
tasks.robot

2. Add libraries to PYTHONPATH
3. In tasks.robot write:

*** Settings ***
Library     Library.py

Expected behavior
Not sure. This functionality of RF doesn't seem to be documented anywhere and works differently than I expected. It is however a difference, so decided to document it here as an issue.

Versions:

• Robot Framework Version: 3.2
• Robot Framework Language Server Version: 0.9.1

Logs
See attached forum post

[pekkaklarck]

It's true that Robot Framework tries to find imports like Library.py from directories in PYTHONPATH. The reason is that it uses the exact same code for finding libraries using a physical path, not name, that is uses to find resource files. This is kind of an accident and I would highly recommend importing libraries by name like Library if they are in PYTHONPATH. Since RF works that way, and there are no plans to remove this support, I guess LSP should support it as well. I just wouldn't consider it too high priority.