assert function in python code example

Example 1: python assert

"""Quick note!
This code snippet has been copied by Pseudo Balls.
This is the original answer.
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"""
"""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: 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 3: 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 4: how to use assert in python

assert type(num) is int,"num must be an integer"

Example 5: python assert

def input_age(age):
   try:
       assert int(age) > 18
   except ValueError:
       return 'ValueError: Cannot convert into int'
   else:
       return 'Age is saved successfully'
 
print(input_age('23'))  	# This will print
print(input_age(25))  		# This will print
print(input_age('nothing')) # This will raise ValueError which is handled
print(input_age('18'))  	# This will raise AssertionError, program collapses
print(input_age(43))  		# This won't print