ImportError: cannot import name 'BaseCommitizen' and others in files starting with `cz_`

Description

As it can be seen in the following line, all files present in the Python environment whose filename begins with cz_ will be discovered and iteratively loaded by commitizen. Unfortunately this also includes files that aren’t in the scope of commitizen but happen to be in PYTHONPATH:

https://github.com/commitizen-tools/commitizen/blob/14b6c382ff96e37ba118ba1b75073b0d2313ee91/commitizen/cz/__init__.py#L18

The reaction is very cryptic and can lead to long and frustrating debugging sessions. Fortunately it is known that the “cannot import” message is linked to circular dependencies, e.g. see https://stackoverflow.com/a/746655

Just importing commitizen doesn’t break, but further recursive imports down the package trigger the issue.

Steps to reproduce

1. Create a file starting with cz_... and call e.g. from commitizen.commands.bump import Bump
2. Run that file with the python interpreter, making sure that the file’s directory is in sys.path
3. The import will trigger an ImportError that is internal to commitizen like the one in the title.

Current behavior

Code that runs from interactive CLI doesn’t run from script

Desired behavior

Code that runs on CLI should also run on script.

Environment

python --version Python 3.6.12 :: Anaconda, Inc. python3 -c “import platform; print(platform.system())”

• commitizen version: 2.4.2
• python version: 3.6
• operating system: Ubuntu

[woile]

I think we should create a new ticket, I still want to refactor the plugin system

[woile]

I’m in, great idea! Let’s coordinate a date