python assert statement code example

Example 1: python assert

"""Quick note!
This code snippet has been copied by Pseudo Balls.
This is the original answer.
Please consider justice by ignoring his answer.
"""
"""assert:
evaluates an expression and raises AssertionError
if expression returns False
"""
assert 1 == 1  # does not raise an error
assert False  # raises AssertionError
# gives an error with a message as provided in the second argument
assert 1 + 1 == 3, "1 + 1 does not equal 3"
"""When line 7 is run:
AssertionError: 1 + 1 does not equal 3
"""

Example 2: python assert statement

name = 'quaid'
# check if name assigned is what assert expects else raise exception
assert(name == 'sam'), f'name is {name}, it should be sam'

print("Hello {check_name}".format(check_name = name))
#output: Assertion Error 
# quaid is not what assert expects rather it expects sam as a string assigned to name variable
# No print out is received

Example 3: assert python

x = "hello"

#if condition returns False, AssertionError is raised:
assert x == "goodbye", "x should be 'hello'"
-----------------------------------------------------------------
Traceback (most recent call last):
  File "demo_ref_keyword_assert2.py", line 4, in <module>
    assert x == "goodbye", "x should be 'hello'"
AssertionError: x should be 'hello'

Example 4: assert syntax python

assert <condition>,<error message>
#The assert condition must always be True, else it will stop execution and return the error message in the second argument
assert 1==2 , "Not True" #returns 'Not True' as Assertion Error.

Example 5: assert keyword in python

The assert keyword is used when debugging code.

The assert keyword lets you test if a condition in your code returns 
True, if not, the program will raise an AssertionError.

You can write a message to be written if the code returns False, check 
the example below.

x = "hello"

#if condition returns False, AssertionError is raised:
assert x == "goodbye", "x should be 'hello'"

Example 6: assert python 3

# Simple asserting thing, run it by using pytest or something 
# If you don't know how to run pytest, then go learn it.

def test_math():
    assert(1 + 1 == 2)

# Another way to test it (without pytest) is:
# You could just run the function to see if it makes an error.
# If it doesn't, it means it was fine, if it does, it means there's an error.

# But then again, using pytest or something is much easier and saves time.
# So try to use testing applications instead of running the function to see.