assert python 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 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 4: 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 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: what is assert

In simple words, if the assert condition is true then the
program control will execute the next test step but if the condition is
false, the execution will stop and further test step will not be executed.