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"""Raising Exceptions.

@see: https://docs.python.org/3/tutorial/errors.html#raising-exceptions

The raise statement allows the programmer to force a specified exception to occur.

"""

def test_raise_exception():

"""Raising Exceptions.

The raise statement allows the programmer to force a specified exception to occur.

"""

exception_is_caught = False

try:

# The sole argument to raise indicates the exception to be raised. This must be either an

# exception instance or an exception class (a class that derives from Exception). If an

# exception class is passed, it will be implicitly instantiated by calling its constructor

# with no arguments

raise NameError('HiThere') # shorthand for 'raise ValueError()'

except NameError:

exception_is_caught = True

assert exception_is_caught

def test_user_defined_exception():

"""User-defined Exceptions"""

# Programs may name their own exceptions by creating a new exception class. Exceptions should

# typically be derived from the Exception class, either directly or indirectly.

# Most exceptions are defined with names that end in “Error,” similar to the naming of the

# standard exceptions. Many standard modules define their own exceptions to report errors

# that may occur in functions they define.

class MyCustomError(Exception):

"""Example of MyCustomError exception."""

def __init__(self, message):

super().__init__(message)

self.message = message

custom_exception_is_caught = False

try:

raise MyCustomError('My custom message')

except MyCustomError:

custom_exception_is_caught = True

assert custom_exception_is_caught