Mockup of an example from a tweet. https://twitter.com/raymondh/statuses/459495133075877888

Using python decorators to define tests for a function.

from testdecorator import test


# Failure: get wrong value
@test(inputs=(2,), expected=0.125)
# Failure: expect value, get exception
@test(inputs=("a",), expected=1000)
# Failure: expect different exception
@test(inputs=([],), expected=ZeroDivisionError)
# Failure: expect exception get value
@test(inputs=(10,), expected=TypeError)
# Pass: expect exception
@test(inputs=(2, 3), expected=TypeError)
# Pass: get expected value
@test(inputs=(3,), expected=27)
def cube(n):
    return n * n * n

Output:

> python3 cube.py
√ cube(3) == 27
√ Called cube(2, 3), Caught expected exception. TypeError: cube() takes 1 positional argument but 2 were given
X Called cube(10), expected TypeError, Got 1000 instead.
X Called cube([]), expected ZeroDivisionError, Caught unexpected exception. TypeError: can't multiply sequence by non-int of type 'list'
X Called cube('a'), expected 1000, Caught unexpected exception. TypeError: can't multiply sequence by non-int of type 'str'
X cube(2) != 0.125. Got 8 instead.