python assert

1assert <condition>,<error message>
2#The assert condition must always be True, else it will stop execution and return the error message in the second argument
3assert 1==2 , "Not True" #returns 'Not True' as Assertion Error.

1In simple words, if the assert condition is true then the
2program control will execute the next test step but if the condition is
3false, the execution will stop and further test step will not be executed.
4

1The assert keyword is used when debugging code.
2
3The assert keyword lets you test if a condition in your code returns 
4True, if not, the program will raise an AssertionError.
5
6You can write a message to be written if the code returns False, check 
7the example below.
8
9x = "hello"
10
11#if condition returns False, AssertionError is raised:
12assert x == "goodbye", "x should be 'hello'"

1def input_age(age):
2   try:
3       assert int(age) > 18
4   except ValueError:
5       return 'ValueError: Cannot convert into int'
6   else:
7       return 'Age is saved successfully'
8 
9print(input_age('23'))  	# This will print
10print(input_age(25))  		# This will print
11print(input_age('nothing')) # This will raise ValueError which is handled
12print(input_age('18'))  	# This will raise AssertionError, program collapses
13print(input_age(43))  		# This won't print

1assert False, "Oh no! This assertion failed!"

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