Pycon_Africa.pdf

Where and How to use Asserts in your Python code!
Best Practices!

Transcript

1. Where and How to use Asserts in your python code ~Prajjwal Nijhara Twitter: @NijharaPrajjwal Github: @pnijhara Blogs: https://pnijhara.github.io
2. The assert statement exists in almost every programming language. It helps detect problems early in your program, where the cause is clear, rather than later as a side-effect of some other operation.
3. How Asserts work?
4. Assert Equivalent to
5. Example
6. Output:
7. Then where is the problem?
8. Python’s -O (optimize) flag
9. During this, these basic optimizations are done: • All the assert statements are removed • All docstrings are removed (when -OO is selected) • Value of the __debug__ built-in variable is set to False What goes down?
10. Let us test the above code with -O flag
11. What can go wrong? If assert statements are used for user-facing validation in production code, the block won’t be executed at all — potentially opening up a security vulnerability.
12. Look how syrusakbary validates mail
13. Fix! It is recommended to use Asserts only in tests.
14. Issue in Mopidy
15. Fix!
16. ~Prajjwal Nijhara Twitter: @NijharaPrajjwal Github: @pnijhara Blogs: https://pnijhara.github.io Thank You!
17. References - https://discuss.deepsource.io/t/using-assert-outside-tests/79 - https://deepsource.io/blog/python-common-mistakes/ - https://github.com/syrusakbary/validate_email/blob/master/validate_email.py#L127 - https://github.com/mopidy/mopidy/issues/1903 - https://github.com/mopidy/mopidy/pull/1904/files - https://deepsource.io