Test language servers with Python 2.7

Refs: https://github.com/microsoft/vscode-python/issues/17225

• macOS @misolori
• windows @brettcannon
• linux @brettcannon

Complexity: 3

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Requirements

1. You will need Python 2.7.16. Options are:
   • You can install it from python.org
   • On Mac/Linux, you can install it using your local package manager
   • For a managed solution that will allow you to install multiple versions of Python you can use pyenv on Mac/Linux, or pyenv-win on Windows, and call pyenv install 2.7.16
2. Install virtualenv with python 2.7: path/to/python2 -m pip install virtualenv
3. Make sure you have "python.experiments.optInto": ["All"], in your user settings. If not, add it and reload VS Code.
4. Make sure the python.defaultInterpreterPath entries in your user and workspace settings are at their default value python
5. Use the latests Insiders build of the Python extension (set python.insidersChannel to daily, wait for the download and installation to happen and reload VS Code)

Scenario 1: Jedi

1. Create a folder with a Python file, and add the following .vscode/settings.json:

{
   "python.languageServer": "Jedi"
}

1. Create a Python 2.7 virtual environment in that folder: /path/to/python2 -m virtualenv .venv
2. Open the folder in VS Code, wait for the extension to load and the virtual environment to get auto-selected
3. In the Python output panel, verify that Editor support is inactive since language server is set to None. is printed, and that language server capabilities are disabled

Scenario 2: Default

1. Create a folder with a Python file, and add the following .vscode/settings.json:

{
   "python.languageServer": "Default"
}

1. Create a Python 2.7 virtual environment in that folder: /path/to/python2 -m virtualenv .venv
2. Open the folder in VS Code, wait for the extension to load and the virtual environment to get auto-selected
3. In the Python output panel, verify that Starting Pylance language server. is printed, and that language server capabilities are working

Scenario 3: Pylance

1. Create a folder with a Python file, and add the following .vscode/settings.json:

{
   "python.languageServer": "Pylance"
}

1. Create a Python 2.7 virtual environment in that folder: /path/to/python2 -m virtualenv .venv
2. Open the folder in VS Code, wait for the extension to load and the virtual environment to get auto-selected
3. In the Python output panel, verify that Starting Pylance language server. is printed, and that language server capabilities are working

[isidorn]

I do not have Python setup on my Linux, thus I have swapped platform assignments with @mjbvz . I hope that is fine.

[brettcannon]

@mjbvz I took you off as I accidentally verified under Linux out of habit from launching VS Code under WSL. 😄 I also went ahead and verified under Windows as well.