Pytest Typing Runner

This is a plugin for pytest to assist in generating scenarios to run static type checking against.

History

This plugin comes out of a fork of the pytest_mypy_plugins pytest plugin for writing tests that pytest can use to run mypy against sets of files.

The difference for this plugin is that it provides a pytest fixture to do work from rather than exposing a yml interface for writing tests. It also allows for running mypy multiple times in the same test with changes to the code being statically type checked. And also has some different mechanisms for expressing the expected output from mypy.

Features

• Provides pytest fixtures to help create scenarios for testing a type checker
• Each scenario is a set of files and a set of expectations around the behaviour of the type checker
• Scenarios may comprise of multiple runs of the type checker to check the behaviour of the type checker when changes are made against a warm cache
• Possible to run the same tests with different "strategies" where a strategy is a combination of specific type checker and default arguments
• Currently only supports mypy by default but should be possible to easily add more type checkers.
• Adds the ability to create files using a syntax for representing expectations in both the style used by mypy tests and a format introduced by this project that in some ways is a bit clearer and more expressive.

Built Docs

https://pytest-typing-runner.readthedocs.io