How To Test Exceptions In Python With Pytest And With Statement

The aim of this page📝 is to demonstrate the syntax for python unit tests (pytest) that pass if an exception is thrown as expected. I have a function validate_and_capitalize where I pass a section_name and section_folders and I need to test if when an improper value is passed, the ValueError with the given message is raised.

Rubberduck of the 👆 function:

1. import pytest
2. pass pytest.raises(Exception) into with statement
3. in the block, call the function that is expected to fail
4. assert exception type with e.type == <exception_type>, e.g. assert e.type == ValueError
5. if needed, assert an error message assert "<error_msg>" in str(e.value), e.g.

links

• How to Check if an Exception Is Raised (or Not) With pytest
• Context Managers and Python’s with Statement — Real Python
• https://realpython.com/python-with-statement/#testing-for-exceptions-with-pytest