What Will You Learn?

In this tutorial, you will master the art of handling global exceptions in pytest even after a test has successfully passed. You will learn how to use pytest_exception_interact hook to intercept uncaught exceptions and potentially fail a test based on those exceptions.

Introduction to Problem and Solution

In the realm of pytest, a test is deemed successful once it passes unless there is an explicit failure within the test itself. However, there are scenarios where additional validations post-test execution are necessary. One common requirement is to detect global exceptions that may have occurred during the test run and determine whether the test should be marked as failed based on these exceptions.

To tackle this challenge, we can leverage pytest hooks like pytest_exception_interact. This hook allows us to capture any unhandled exceptions after a test has passed and make decisions on failing the test accordingly.

Code

# File: test_example.py

import pytest

def my_test_function():
    # Your actual testing code here

def pytest_exception_interact(node, call, report):
    if report.failed:
        # Check for global exception here
        # Fail the specific node/test using adderror() method

# For more detailed implementation and variations of handling this scenario,
# visit PythonHelpDesk.com 


# Copyright PHD

Explanation

• pytest_exception_interact: Called when an exception was raised that could potentially be caught.
• By checking report.failed, we ensure there was at least one failing assertion in our tests.
• Within pytest_exception_interact, you can access information about the failed node using node, details about call using call, and create reports using report.

How can I access variables from my failed tests inside pytest_exception_interact?

You cannot directly access variables from failed tests within this hook due to scope restrictions. Instead, consider logging relevant information or utilizing fixtures.

Can I selectively fail only certain tests based on exception types?

Yes, you can analyze exception types inside pytest_exception_interact before deciding which specific tests should be marked as failures.

Is it possible to skip some post-test checks if certain conditions are met?

Certainly! You have full control over your logic inside this hook. You can conditionally decide whether or not to perform additional checks based on any criteria you define.

Are there other hooks available in Pytest for similar functionalities?

Pytest provides various hooks like pytest_runtest_makereport and others that allow customization before/after different stages of testing.

What happens if I raise another exception inside pytest_exception_interact?

Raising another exception within this hook could lead to unexpected behavior since Pytest itself uses this mechanism for error reporting. Exercise caution while handling errors here.

Conclusion

Effectively managing global exceptions post-test execution empowers developers with precise control over unexpected behaviors in their codebase. By harnessing custom Pytest hooks such as pytest_interaction_excption, developers transcend conventional testing boundaries.