How to check for leakage of test/dev dependencies in main code

[soxofaan]

(disclaimer: this is not a pure pytest related question, but this felt like a good place to raise anyway)

Say you have a project which defines test dependencies. These test dependencies should only be used in the test code, but how do you ensure that they are not leaking accidentally in the main, non-test code (e.g. uncareful committing import statements that were added by some autocomplete feature of your IDE)?

You can not catch this problem (e.g. looking for ImportErrors) with a normal pytest run, because the dependencies will be available in the test environment. Inversely, you can not run your tests in an environment without the test dependencies either.

Are there any approaches, tools, pytest plugins or trick to automatically check for leaking test (or more generally development) dependencies in your main code?
Any pointers to address this would be appreciated.

[RonnyPfannschmidt]

Mypy check of just the codebase should error in a venv thats missing test deps

[nicoddemus]

One alternative is to configure a https://github.com/seddonym/import-linter as a pre-commit hook.