@pytest.mark.xfail for expected failures - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of a test marked with @pytest.mark.xfail

What will be the test result when running this pytest test marked with @pytest.mark.xfail and the test fails as expected?

PyTest

import pytest

@pytest.mark.xfail
def test_example():
    assert 1 == 2

A The test is reported as failed.

B The test is reported as passed.

C The test is reported as xfailed (expected failure).

D The test is skipped.

💡 Hint

Think about what @pytest.mark.xfail means when the test fails.

When a test marked with @pytest.mark.xfail fails, pytest reports it as xfailed, meaning the failure was expected and does not count as a failure.

❓ assertion

intermediate

Assertion behavior with @pytest.mark.xfail and strict=True

Given this test marked with @pytest.mark.xfail(strict=True), what happens if the test passes unexpectedly?

PyTest

import pytest

@pytest.mark.xfail(strict=True)
def test_strict_xfail():
    assert 1 == 1

A The test is reported as xpassed (unexpected pass).

B The test is reported as passed.

C The test is reported as failed.

D The test is skipped.

💡 Hint

What does strict=True do when the test passes?

With strict=True, if a test marked xfail passes, pytest reports it as xpassed, indicating an unexpected pass.

🔧 Debug

advanced

Identify why a test marked with @pytest.mark.xfail is reported as failed

Why does this test marked with @pytest.mark.xfail fail instead of being reported as xfailed?

PyTest

import pytest

@pytest.mark.xfail(raises=AssertionError)
def test_bug():
    assert 'a' in 'apple'
    raise ValueError('bug')

A Because the test has multiple assertions and only the last fails, pytest reports failure.

B Because the test raises an unexpected exception type (not AssertionError), pytest reports it as failed, not xfailed.

C Because the first assertion passes, pytest ignores the xfail mark.

D Because the test fails, it should be reported as xfailed, so this is a pytest bug.

💡 Hint

Consider what kinds of failures @pytest.mark.xfail expects.

If the test raises an unexpected exception type (not AssertionError), pytest reports it as failed, not xfailed.

🧠 Conceptual

advanced

Purpose of @pytest.mark.xfail in test suites

What is the main purpose of using @pytest.mark.xfail in a test suite?

A To mark tests that are expected to fail due to known bugs or incomplete features.

B To skip tests that are not ready to run yet.

C To mark tests that should always pass regardless of code changes.

D To mark tests that should run slower for performance reasons.

💡 Hint

Think about tests that fail but you want to keep in the suite.

The xfail mark is used to indicate tests that are expected to fail, often due to known bugs or unfinished features, so their failures don't break the test suite.

❓ framework

expert

Behavior of @pytest.mark.xfail with condition and reason

Consider this test marked with @pytest.mark.xfail(condition, reason). What happens if the condition is False?

PyTest

import pytest

@pytest.mark.xfail(condition=False, reason="Known bug")
def test_conditional_xfail():
    assert False

A The test is reported as passed even if it fails.

B The test is skipped because the condition is False.

C The test is reported as xfailed regardless of the condition.

D The test runs normally and failure is reported as a failure, not xfail.

💡 Hint

What does the condition parameter control in xfail?

If the condition is False, the xfail mark is ignored and the test runs normally; failures are reported as failures.