PYTHON

assert keyword python

"""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
"""

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'

assert in python

# AssertionError with error_message.
x = 1
y = 0
assert y != 0, "Invalid Operation" # denominator can't be 0
print(x / y)

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'"

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

assert in python

x = "aaa"

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

python assert

assert False, "Oh no! This assertion failed!"

assert in python

a = 5
assert a == 5 # True
assert a == 42 # False, the program fails

#OUTPUT
Traceback (most recent call last):
  File "none.py", line 155, in <module>
    assert a == 42
AssertionError