Expect fail

The expect_fail tag is used to mark a test as expected to fail. When a test marked with expect_fail fails, it is considered a success. When a test marked with expect_fail passes, it is considered a failure.

Basic Usage

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import karva

@karva.tags.expect_fail
def test_function():
    assert False

Then running uv run karva test will result in one passed test.

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import karva

@karva.tags.expect_fail()
def test_function():
    assert False

Then running uv run karva test will result in one passed test.

Reason

You can provide a str reason as a positional or keyword argument.

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import karva

@karva.tags.expect_fail("This test is expected to fail")
def test_function():
    assert False

Then running uv run karva test will result in one passed test.

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import karva

@karva.tags.expect_fail(reason="This test is expected to fail")
def test_function():
    assert False

Then running uv run karva test will result in one passed test.

The reason only shows when the test passes when expected to fail.

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import karva

@karva.tags.expect_fail(reason="This test is expected to fail")
def test_function():
    assert True

Then running uv run karva test will result in one failed test.

Pytest

We can also still use @pytest.mark.xfail.

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import pytest

@pytest.mark.xfail(reason="This test is expected to fail")
def test_function():
    assert False

Then running uv run karva test will result in one passed test.

Conditions

We can provide bool conditions as a positional arguments.

Then the test will only be expected to fail if all conditions are True.

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import karva

@karva.tags.expect_fail(True)
def test_function():
    assert False

Then running uv run karva test will result in one passed test.

You can still provide a reason as a keyword argument.

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import karva

@karva.tags.expect_fail(True, reason="Waiting for feature X to be implemented")
def test_function():
    assert False

Then running uv run karva test will result in one passed test.

Multiple Conditions

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import karva

@karva.tags.expect_fail(True, False)
def test_function():
    assert True

Then running uv run karva test will result in one failed test.