Python unittest - opposite of assertRaises?

Unmasking unittest: The inner workings

In the unittest framework's world, a test method doesn't just pass—it waltzes to completion without tripping on an exception. Here, test failures are totally different from tests with errors. A failure? That's when an assertion pulls a face. An error? That's an uninvited exception. Knowing this helps you write precise tests and interpret their results like a pro.

The assertNotRaises offspring: Subclassing unittest

True, unittest hasn't blessed us with a built-in assertNotRaises. But, like a DIY enthusiast, you can roll it yourself. Put your subclassing hat on, and behold:

import unittest

class ExtendedTestCase(unittest.TestCase):
    def assertNotRaises(self, exception, callable, *args, **kwargs):
        try:
            callable(*args, **kwargs)
        except exception as e:
            self.fail(f"{exception} barged in like an uninvited houseguest: {e}")
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Paint a clear picture: Writing crystal-clear tests

Double down on comments when writing your tests, clearly stating why no exceptions should pop up. Unexpected exceptions: let's treat them as outright errors. The stack trace, that's our Sherlock Holmes, figuring out what went wrong.

Burn the rulebook: Best practices for no-raise scenarios

• Write tests like the daredevil you are—assume they'll sail through without tripping on exceptions.
• Use trusty old try blocks to wrap the code bits you're testing.
• Keep exceptions under check, especially those tied to your app's logic.
• Use your hidden weapon: self.fail(), sitting quietly within the except block, ready to yell "failure" if an exception pops up.

Juggling exceptions: Handling them in unit tests

Master the art of handling exceptions using try-except blocks, knowing that how you customize your except clause isn't just important—it's critical. Make sure you catch the type of exception you expect, keeping other bugs under wraps. After all, granular control keeps the unexpected exceptions at bay and your tests en route to success.

Express yourself: Adding clarity to tests

Use your words: comment and use clear naming conventions to highlight your expectations from the tests. Aim for quick comprehension and instant recognition of a successful outcome.

Success is golden: Emphasizing successful execution

Sometimes, the lack of drama (or error) is the real win. A test method like assertNotRaises underlines this expected success in your test case. This makes the intent of the test clear, ruling out any ambiguities.

Staying flexible: Handling different scenarios

For scenarios where certain exceptions are not entirely unwelcome, contextlib.suppress is your buddy. This feature lets you suppress exceptions temporarily within a given context.