Quickstart

Check that a pytest test raises an expected exception:

from pytest_issues import raises

@raises(ValueError, 'some message A', 'another message B', third message C')
def test():
    raise ValueError(
        "This test must raise a ValueError that includes some message A, "
        "another message B, and a third message C."
    )

@raises((ValueError, TypeError), 'some message')
def test_multiple_types():
    raise TypeError(
        "This test must raise either a ValueError or a TypeError, "
        "and must report some message."
    )

---

Auto-fail to inspect error messages:

@raises(ValueError)
def test_autofail():
    raise ValueError(
        "The call to @raises does not include a message string, so this test "
        "will automatically fail and display the raised message in the "
        "pytest output"
    )

---

Inject fixtures and parameters into expected error messages:

@raises(ValueError, 'some info about {param1} and {fixture2}')
@pytest.mark.parametrize('param1', ('test1', 'test2', 'test3'))
def test_format_message(param1, fixture1, fixture2):
    raise ValueError(
        f"Each test must raise an exception with some info about {param1} "
        f"and {fixture2}."
    )

---

Check a test issues a warning:

from pytest_issues import warns
import warnings

@warns(RuntimeWarning, "some warning message")
def test_warning():
    warnings.warn(
        "This test must issue some warning message",
        RuntimeWarning,
    )