Assert — Python Technical Interview Questions & Answers

Assert

Assert

  • assert condition, "msg" checks a belief while developing. If False, AssertionError. Good for internal checks, not for user input validation in production (can be disabled with python -O).
  • Example: assert marks >= 0. If marks is -5, the script stops with a clear message.
  • Output: ok 72. If marks were -5, AssertionError. python -O can skip asserts.

Technical Interview Tip: What assert does + python -O warning.

Code Examples for Assert

Example

# Assert
marks = 72
assert marks >= 0, "marks cannot be negative"
print("ok", marks)

Output: ok 72. If marks were -5, AssertionError. python -O can skip asserts.

How to Explain Assert to an Interviewer

Explain Assert as if you are teaching a junior — definition, then one tiny script.

assert checks a condition. False → AssertionError.

What does the example print, and why?

ok 72

What mistake do freshers make with Assert?

False → AssertionError.