Python Testing: Write Tests That Actually Catch Bugs
You’ve written a test that passes, but your bug still slipped through. Why? Because you tested the path the code took, not the outcome the user actually needs. Most Python tests fail to catch bugs because they’re written to verify implementation details instead of real behaviors. The fix isn’t more tests—it’s smarter ones.
Let’s fix that.
Test Behavior, Not Implementation
The single biggest mistake in Python testing is writing tests that check how code works instead of what it does. You might assert that a function called save_to_database() exactly once, but if the database silently drops the record, your test passes and your user loses data.
