pytest-timeout for time limits - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What happens when a test exceeds the timeout?

Consider this pytest test using pytest-timeout to limit execution time to 1 second.

import time
import pytest

@pytest.mark.timeout(1)
def test_sleep():
    time.sleep(2)

What is the test result when you run this?

PyTest

import time
import pytest

@pytest.mark.timeout(1)
def test_sleep():
    time.sleep(2)

A The test fails due to timeout after 1 second.

B The test passes because sleep is allowed to finish.

C The test raises a SyntaxError because of incorrect decorator usage.

D The test is skipped automatically by pytest.

💡 Hint

Think about what pytest-timeout does when a test runs longer than allowed.

The @pytest.mark.timeout(1) decorator stops the test if it runs longer than 1 second. Since time.sleep(2) sleeps for 2 seconds, the test fails due to timeout.

❓ assertion

intermediate

Which assertion correctly checks timeout exception?

You want to test that a function long_task() times out after 1 second using pytest-timeout. Which assertion correctly verifies the timeout?

PyTest

import pytest

@pytest.mark.timeout(1)
def test_long_task():
    long_task()

A

with pytest.raises(pytest.TimeoutException):
    long_task()

B assert long_task() == 'timeout'

C assert long_task() is None

D

with pytest.raises(TimeoutError):
    long_task()

💡 Hint

Check which exception pytest-timeout raises on timeout.

pytest-timeout raises TimeoutError when a test times out. So the correct way to assert timeout is using pytest.raises(TimeoutError).

🔧 Debug

advanced

Why does the timeout not stop the test?

This test uses pytest-timeout but the test runs longer than the timeout without stopping:

import time
import pytest

@pytest.mark.timeout(1)
def test_wait():
    time.sleep(3)

What is the most likely reason the timeout is ignored?

A The test is run with <code>pytest --timeout=0</code> which disables timeout.

B The <code>@pytest.mark.timeout</code> decorator is misspelled.

C The <code>pytest-timeout</code> plugin is not installed or not active.

D The test function name does not start with 'test_'.

💡 Hint

Check if the plugin is installed and enabled.

If pytest-timeout is not installed or not enabled, the @pytest.mark.timeout decorator has no effect and tests run without timeout.

❓ framework

advanced

How to set a global timeout for all tests?

You want to apply a 2-second timeout to all tests in your pytest suite without adding decorators to each test. Which is the best way?

A Add <code>--timeout=2</code> option in pytest command line or pytest.ini config.

B Set <code>timeout=2</code> inside each test function body.

C Add <code>@pytest.mark.timeout(2)</code> to each test function manually.

D Use <code>pytest.set_timeout(2)</code> in conftest.py.

💡 Hint

Think about pytest configuration options.

You can set a global timeout by passing --timeout=2 on the command line or adding timeout = 2 under the [pytest] section in pytest.ini. This applies timeout to all tests automatically.

🧠 Conceptual

expert

What is the effect of timeout_method=thread in pytest-timeout?

pytest-timeout supports different timeout methods. What happens when you set timeout_method=thread?

A The test process is forcibly killed immediately on timeout.

B The test is stopped by raising an exception in a separate thread without killing the process.

C Timeout is ignored and tests run without limits.

D The test is paused and resumed after timeout.

💡 Hint

Consider how threads can interrupt test execution.

With timeout_method=thread, pytest-timeout uses a separate thread to raise a timeout exception inside the test thread. This stops the test by exception without killing the whole process.

Practice

1. What is the main purpose of using pytest-timeout in test cases?

easy

A. To stop tests that run longer than a specified time limit

B. To increase the speed of test execution by skipping tests

C. To automatically retry failed tests

D. To generate detailed test coverage reports

Solution

1. Step 1: Understand pytest-timeout functionality

   pytest-timeout is designed to stop tests that exceed a time limit to prevent long waits.

2. Step 2: Compare options with pytest-timeout purpose

   Only To stop tests that run longer than a specified time limit matches this purpose; others describe different pytest features.

3. Final Answer:

   To stop tests that run longer than a specified time limit -> Option A

4. Quick Check:

   pytest-timeout stops long tests = C [OK]

Hint: Remember: pytest-timeout stops tests running too long [OK]

Common Mistakes:

• Confusing timeout with test retries
• Thinking it speeds up tests by skipping
• Mixing it with coverage reporting

2. Which of the following is the correct way to set a 5-second timeout for a test function using pytest-timeout?

easy

A. @pytest.mark.timeout(seconds=5)
def test_example(): pass

B. @pytest.timeout(5)
def test_example(): pass

C. @pytest.mark.timeout(5)
def test_example(): pass

D. @pytest.timeout(seconds=5)
def test_example(): pass

Solution

1. Step 1: Recall correct pytest-timeout decorator syntax

   The correct decorator is @pytest.mark.timeout(5) using a positional argument.

2. Step 2: Check each option's syntax

   @pytest.mark.timeout(5) def test_example(): pass uses correct syntax with positional argument 5. @pytest.mark.timeout(seconds=5) def test_example(): pass incorrectly uses keyword argument 'seconds=5'. The options using @pytest.timeout use wrong decorator names.

3. Final Answer:

   @pytest.mark.timeout(5) def test_example(): pass -> Option C

4. Quick Check:

   Use @pytest.mark.timeout(5) = A [OK]

Hint: Use @pytest.mark.timeout(5) to set 5 seconds [OK]

Common Mistakes:

• Using @pytest.timeout instead of @pytest.mark.timeout
• Passing seconds as a keyword argument
• Missing the @pytest.mark prefix

3. Given the following test code, what will happen when running pytest?

@pytest.mark.timeout(2)
def test_sleep():
    import time
    time.sleep(3)

medium

A. The test will pass because sleep is allowed

B. The test will raise a syntax error

C. The test will be skipped automatically

D. The test will fail due to exceeding the 2-second timeout

Solution

1. Step 1: Analyze the timeout and sleep duration

   The test has a 2-second timeout but sleeps for 3 seconds, exceeding the limit.

2. Step 2: Understand pytest-timeout behavior on timeout

   pytest-timeout stops the test and marks it as failed if it runs longer than the timeout.

3. Final Answer:

   The test will fail due to exceeding the 2-second timeout -> Option D

4. Quick Check:

   Sleep 3s > timeout 2s = fail [OK]

Hint: If test runs longer than timeout, it fails [OK]

Common Mistakes:

• Assuming test passes despite timeout
• Thinking test is skipped automatically
• Confusing timeout with syntax errors

4. Identify the error in the following pytest test using pytest-timeout:

@pytest.mark.timeout(3)
def test_loop():
    for i in range(5):
        time.sleep(1)

medium

A. Timeout value is too low for the loop

B. Missing import of the time module

C. Incorrect decorator syntax

D. The test will pass without errors

Solution

1. Step 1: Check for missing imports

   The test uses time.sleep(1) but does not import the time module.

2. Step 2: Verify other aspects

   The timeout and decorator syntax are correct. The missing import will cause a NameError.

3. Final Answer:

   Missing import of the time module -> Option B

4. Quick Check:

   Using time.sleep without import = error [OK]

Hint: Always import modules before using their functions [OK]

Common Mistakes:

• Ignoring missing imports
• Assuming timeout causes error instead
• Thinking decorator syntax is wrong

5. You want to apply a 10-second timeout to all tests in a pytest file without adding @pytest.mark.timeout to each test. Which is the best way to do this?

hard

A. Add pytestmark = pytest.mark.timeout(10) at the top of the test file

B. Set timeout=10 in pytest.ini configuration file

C. Use @pytest.mark.timeout(10) on a dummy test and inherit it

D. Add timeout=10 as a command line argument every time

Solution

1. Step 1: Understand pytestmark usage

   Setting pytestmark = pytest.mark.timeout(10) applies the timeout decorator to all tests in the file automatically.

2. Step 2: Evaluate other options

   Adding timeout as a command line argument requires specifying --timeout=10 every time pytest is run; setting timeout in pytest.ini applies it globally to all tests in the project; using a dummy test for inheritance is not a valid pytest feature. pytestmark is best for this specific file.

3. Final Answer:

   Add pytestmark = pytest.mark.timeout(10) at the top of the test file -> Option A

4. Quick Check:

   pytestmark applies decorator to all tests [OK]

Hint: Use pytestmark variable to apply timeout to all tests [OK]

Common Mistakes:

• Trying to set timeout in pytest.ini (global, not file-specific)
• Using dummy test inheritance (not valid)
• Relying on command line timeout argument (inconvenient)