Pytest Examples: Handling Exceptions

Pytest Examples: Handling Exceptions

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Python 3x+, Pytest 7x+ used unless otherwise stated.

Assert exception is raised

Use with pytest.raises(ValueError): as a context manager:

# inside my_test.py
def test_raises_index_error():

    # test will success if an IndexError is raised
    with pytest.raises(IndexError):
        arr = [1,2,3]
        arr[1]

Assert exception with specific text

Use pytest.raises(<class>, match=<regular_expression>). <regular_expression> supports whatever you can use in re.search.

# inside my_test.py
def test_raises_specific_exception():

    # test will success if a ValueError is raised,
    # but only if the text contains a number starting with "5"
    # (e.g. 500 or 503 HTTP errors)
    with pytest.raises(RuntimeError, match=r"5\d+"):
        some_code_that_raises_the_exception()

python pytest

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