assert

KeywordPython 2.0+Intermediate

Debugging aid that tests a condition and raises AssertionError if false

Quick Info

Documentation: Official Docs
Python Version: 2.0+

Learn by Difficulty

Easy1 example

Examples|Playground

Intermediate2 examples

Quick Example

python

x = 10
assert x > 0, "x must be positive"
print("x is valid")

# Assert with expressions
name = "Alice"
assert len(name) > 0, "Name cannot be empty"
print(f"Name: {name}")

# Catching assertion errors
try:
    temperature = -300
    assert temperature > -273.15, f"Temperature {temperature} is below absolute zero"
except AssertionError as e:
    print(f"Invalid: {e}")