Testing custom exceptions in PyTest - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if the function raises ValueError.

PyTest

import pytest

def test_raise_custom_exception():
    with pytest.raises([1]):
        raise ValueError('Error!')

Drag options to blanks, or click blank then click option'

AKeyError

BValueError

CTypeError

DIndexError

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different exception type than the one raised.

Not using pytest.raises() to catch exceptions.

The pytest.raises() expects the exception type that the code inside the block will raise. Here, ValueError is raised, so the test passes only if ValueError is used.

2fill in blank

medium

Complete the code to define a custom exception class.

PyTest

class [1](Exception):
    pass

Drag options to blanks, or click blank then click option'

ACustomError

Berror

Cexception

DError

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase names for exception classes.

Not inheriting from Exception.

Custom exception classes should be named clearly and start with a capital letter. CustomError is a good descriptive name.

3fill in blank

hard

Fix the error in the test to correctly check for the custom exception.

PyTest

import pytest

class MyError(Exception):
    pass

def test_my_error():
    with pytest.raises([1]):
        raise MyError('Oops!')

Drag options to blanks, or click blank then click option'

AMyError

BMyerror

CException

DError

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong capitalization for the exception class name.

Using a base exception class instead of the custom one.

The exception class name is case-sensitive. The correct name is MyError with capital E.

4fill in blank

hard

Fill both blanks to raise and test a custom exception with a message.

PyTest

import pytest

class CustomError(Exception):
    pass

def test_custom_error_message():
    with pytest.raises([1]) as exc_info:
        raise CustomError([2])
    assert str(exc_info.value) == 'Error occurred'

Drag options to blanks, or click blank then click option'

ACustomError

B'Error occurred'

C'An error happened'

DException

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different exception class in pytest.raises().

Passing a different message string than the one asserted.

The test checks that CustomError is raised with the exact message 'Error occurred'. The pytest.raises() captures the exception to verify its message.

5fill in blank

hard

Fill all three blanks to define, raise, and test a custom exception with a message.

PyTest

import pytest

class [1](Exception):
    pass

def test_[2]():
    with pytest.raises([3]) as exc:
        raise CustomException('Failed')
    assert str(exc.value) == 'Failed'

Drag options to blanks, or click blank then click option'

ACustomException

Bcustom_exception

DCustomError

Attempts:

3 left

💡 Hint

Common Mistakes

Mismatch between class name and exception caught.

Incorrect test function naming style.

Using a different exception class in the test.

The class name is CustomException. The test function name is test_custom_exception (snake_case). The exception caught is CustomException. This matches the raised exception and message.