Built-in markers (skip, skipif, xfail) in PyTest - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of pytest with skip marker

What will be the test execution result when running this pytest code?

PyTest

import pytest

@pytest.mark.skip(reason="Not ready yet")
def test_example():
    assert 1 == 1

A The test is skipped and reported as skipped.

B The test runs and passes.

C The test runs and fails.

D SyntaxError occurs due to incorrect marker usage.

💡 Hint

The skip marker tells pytest not to run the test but to mark it as skipped.

The @pytest.mark.skip decorator prevents the test from running and pytest reports it as skipped with the given reason.

❓ Predict Output

intermediate

Behavior of skipif marker with condition

What will pytest report when running this test on a Linux system?

PyTest

import pytest
import sys

@pytest.mark.skipif(sys.platform != 'linux', reason='Only runs on Linux')
def test_linux_only():
    assert True

A Test always runs and passes regardless of OS.

B Test runs and passes on Linux; skipped on other OS.

C Test always skipped regardless of OS.

D Test fails with ImportError.

💡 Hint

skipif skips the test only if the condition is True.

The test runs only if sys.platform is 'linux'. On Linux it runs and passes; on other OS it is skipped.

❓ assertion

advanced

Assertion outcome with xfail marker

Given this pytest test marked with xfail, what is the final test report status if the assertion fails?

PyTest

import pytest

@pytest.mark.xfail(reason='Known bug')
def test_buggy():
    assert 1 == 2

A Test is skipped.

B Test is reported as failed.

C Test is reported as passed.

D Test is reported as xfailed (expected failure).

💡 Hint

xfail marks tests expected to fail without failing the suite.

When a test marked xfail fails, pytest reports it as xfailed, meaning expected failure, not a failure.

❓ Predict Output

advanced

xfail with passing test behavior

What will pytest report if a test marked with xfail actually passes?

PyTest

import pytest

@pytest.mark.xfail(reason='Known bug')
def test_fixed():
    assert 2 == 2

A Test is reported as xpassed (unexpected pass).

B Test is reported as failed.

C Test is reported as passed.

D Test is skipped.

💡 Hint

xfail expects failure; passing is unexpected.

If a test marked xfail passes, pytest reports it as xpassed, meaning it passed unexpectedly.

🔧 Debug

expert

Identify the error in skipif usage

Which option correctly identifies the error in this pytest code snippet?

PyTest

import pytest
import sys

@pytest.mark.skipif(sys.platform == "win32", reason='Skip on Windows')
def test_func():
    assert True

A The condition is a string and should be a boolean expression, causing the test to always skip.

B The reason parameter is missing, causing a TypeError.

C There is no error; the code runs and skips on Windows.

D The skipif marker is used incorrectly; it should be skip instead.

💡 Hint

skipif expects a boolean condition, not a string.

The condition is a boolean expression, so the test skips only on Windows as intended.

Practice

1. What does the @pytest.mark.skip marker do in a test?

easy

A. It retries the test multiple times before failing.

B. It runs the test only if a condition is true.

C. It marks the test as expected to fail but still runs it.

D. It always skips the test, so it does not run.

Solution

1. Step 1: Understand the purpose of @pytest.mark.skip

   This marker tells pytest to skip the test unconditionally, so the test is not executed at all.

2. Step 2: Compare with other markers

   skipif skips conditionally, and xfail marks expected failures but runs the test. So only skip always skips.

3. Final Answer:

   It always skips the test, so it does not run. -> Option D

4. Quick Check:

   @pytest.mark.skip always skips = D [OK]

Hint: Skip always means test won't run at all [OK]

Common Mistakes:

• Confusing skip with skipif (conditional skip)
• Thinking xfail skips the test
• Assuming skip reruns the test

2. Which of the following is the correct syntax to skip a test only if Python version is less than 3.8?

easy

A. @pytest.mark.skipif(sys.version_info < (3, 8)\ndef test_func(): pass

B. @pytest.mark.skipif(sys.version_info < (3, 8), reason='Python < 3.8')\ndef test_func(): pass

C. @pytest.mark.skipif(sys.version_info < 3.8)\ndef test_func(): pass

D. @pytest.mark.skipif(sys.version_info < '3.8')\ndef test_func(): pass

Solution

1. Step 1: Check correct version tuple comparison syntax

   Python version info is a tuple like (3, 7, 5). So comparisons must use tuples, e.g., (3, 8).

2. Step 2: Verify correct use of skipif with reason

   @pytest.mark.skipif(sys.version_info < (3, 8), reason='Python < 3.8')\ndef test_func(): pass uses tuple comparison and includes a reason string, which is best practice for clarity.

3. Final Answer:

   @pytest.mark.skipif(sys.version_info < (3, 8), reason='Python < 3.8')\ndef test_func(): pass -> Option B

4. Quick Check:

   Use tuple and reason in skipif = C [OK]

Hint: Use tuple for version and add reason in skipif [OK]

Common Mistakes:

• Using float instead of tuple for version
• Omitting reason argument
• Comparing version to string

3. What will be the test result when running this code?

import pytest

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

medium

A. Test is marked as expected failure but does not fail the suite.

B. Test fails and is reported as failed.

C. Test passes because xfail ignores failures.

D. Test is skipped and not run.

Solution

1. Step 1: Understand @pytest.mark.xfail behavior

   This marker means the test is expected to fail. If it fails, pytest reports it as an expected failure, not a hard failure.

2. Step 2: Analyze the assertion

   The assertion 1 == 2 is false, so the test fails. Because of xfail, this failure is expected and reported accordingly.

3. Final Answer:

   Test is marked as expected failure but does not fail the suite. -> Option A

4. Quick Check:

   xfail means expected failure = A [OK]

Hint: xfail means failure is expected, not a hard fail [OK]

Common Mistakes:

• Thinking xfail skips the test
• Assuming test passes despite assertion
• Confusing xfail with skipif

4. Identify the error in this pytest code snippet:

import pytest

@pytest.mark.skipif(sys.platform == 'win32')
def test_func():
    assert True

medium

A. Missing import of sys module causes NameError.

B. skipif should be skip to always skip the test.

C. The condition syntax is incorrect; should use double equals.

D. The test function must return a value.

Solution

1. Step 1: Check imports used in condition

   The condition uses sys.platform, but sys is not imported, causing a NameError at runtime.

2. Step 2: Verify other parts

   The condition syntax is correct with ==, skipif is valid, and test functions do not need to return values.

3. Final Answer:

   Missing import of sys module causes NameError. -> Option A

4. Quick Check:

   Missing import sys = A [OK]

Hint: Always import modules used in skipif conditions [OK]

Common Mistakes:

• Forgetting to import sys
• Confusing skipif with skip
• Expecting test functions to return values

5. You want to mark a test that should be skipped on Windows and expected to fail on Python versions below 3.7. Which is the correct way to combine skipif and xfail markers?

hard

A. @pytest.mark.xfail(sys.version_info < (3,7, reason='Expected fail on old Python')\[e-mail](sys.platform == 'win32', reason='Skip on Windows')\ndef test_func(): pass

B. @pytest.mark.skipif(sys.platform == 'win32' and sys.version_info < (3,7))\ndef test_func(): pass

C. @pytest.mark.skipif(sys.platform == 'win32', reason='Skip on Windows')\[e-mail](sys.version_info < (3,7), reason='Expected fail on old Python')\ndef test_func(): pass

D. @pytest.mark.skipif(sys.platform == 'win32')\[e-mail](sys.version_info < (3,7))\ndef test_func(): pass

Solution

1. Step 1: Understand marker order and logic

   Tests should be skipped on Windows unconditionally, so skipif for Windows must be applied first.

2. Step 2: Apply xfail conditionally for Python versions below 3.7

   The xfail marker is applied second to mark expected failures on old Python versions.

3. Step 3: Verify option correctness

   @pytest.mark.skipif(sys.platform == 'win32', reason='Skip on Windows')\[e-mail](sys.version_info < (3,7), reason='Expected fail on old Python')\ndef test_func(): pass applies skipif first, then xfail, both with reasons. This is the correct and clear approach.

4. Final Answer:

   Use skipif for Windows, then xfail for Python version condition with reasons. -> Option C

5. Quick Check:

   Skip first, then xfail with reasons = B [OK]

Hint: Apply skipif first, then xfail with clear reasons [OK]

Common Mistakes:

• Reversing marker order causing unexpected runs
• Combining conditions incorrectly in one skipif
• Omitting reason strings for markers