Скачать или смотреть How to Use pytest.skip for Specific Exceptions in Your Test Suite

Learn how to effectively use the `pytest.skip` feature to manage exceptions like `FileNotFoundError` in your Python tests, enhancing test reliability and coverage.
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This video is based on the question https://stackoverflow.com/q/63517507/ asked by the user 'Rivian' ( https://stackoverflow.com/u/13546300/ ) and on the answer https://stackoverflow.com/a/63522579/ provided by the user 'lucrib' ( https://stackoverflow.com/u/3586361/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Handling Exceptions in pytest: Skipping Tests with pytest.skip

When developing tests in Python using the pytest framework, one common challenge developers face is how to handle exceptions gracefully. It’s particularly useful to skip tests when certain conditions, such as missing files, are not met. In this guide, we will explore a case involving pytest.skip for the FileNotFoundError exception and provide a practical solution that you can integrate into your testing suite.

The Problem

Imagine you have a set of test cases that validate the contents of a target file. If the target file does not exist, running the test should not produce a failure; instead, it should simply skip the test and provide a clear message indicating why the test was skipped. In your initial implementation, you might have code like this:

[[See Video to Reveal this Text or Code Snippet]]

To handle the case where the target file is missing, you modified your code to include a try-except block:

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While this works, repeating this pattern across many test cases can be tedious and error-prone.

The Challenge with pytest_exception_interact

You attempted to centralize your handling of FileNotFoundError by implementing a hook in conftest.py like so:

[[See Video to Reveal this Text or Code Snippet]]

Unfortunately, this led to an INTERNALERROR, which indicates that an exception was raised inside the hook implementation. This is because the pytest.skip call should not occur within this context as it raises another exception instead of marking the test as skipped.

The Solution: A Custom Decorator

Instead of utilizing a hook, consider creating a custom decorator for your test functions. This allows you to elegantly wrap your test cases and handle exceptions directly. Here’s an example of how to implement this:

Step 1: Create the Decorator

Define a decorator function that catches specified exceptions and raises pytest.skip accordingly.

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Step 2: Use the Decorator in Your Tests

Now that you have defined the decorator, you can easily apply it to your tests:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

Using pytest.skip effectively can greatly enhance the maintainability and clarity of your test suite. By implementing a reusable decorator, you ensure that any necessary exception handling is handled consistently across your tests, reducing redundancy and increasing reliability.

If you frequently encounter situations where skipping tests is beneficial, investing time in creating such utilities will pay off in the long run. This approach not only improves your code but also makes it easier for others to understand and contribute to your testing efforts.

Happy testing!