Test packages in PyTest - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding pytest test package structure

Which of the following directory structures correctly represents a pytest test package that will be automatically discovered and run by pytest?

A project_root/tests/test_module.txt

B project_root/tests/__init__.py and project_root/tests/test_module.py

C project_root/test_module.py only

D project_root/tests/test_module.py

💡 Hint

pytest discovers tests in files named test_*.py or *_test.py in any directory, even without __init__.py.

pytest discovers test files named test_*.py or *_test.py recursively in directories, even if they don't have __init__.py. Option D is correct because it has a test file in a directory named tests. Option D is not necessary for pytest discovery.

❓ Predict Output

intermediate

pytest test package import behavior

Given the following package structure and test code, what will be the output when running pytest from project_root?

project_root/
  mypackage/
    __init__.py
    utils.py
  tests/
    __init__.py
    test_utils.py

# test_utils.py content:
import mypackage.utils

def test_example():
    assert mypackage.utils.func() == 42

# utils.py content:
def func():
    return 42

A Test passes successfully

B ImportError: No module named 'mypackage.utils'

C AssertionError because func() returns wrong value

D SyntaxError in test_utils.py

💡 Hint

pytest adds the project root to sys.path, so imports from sibling packages work.

pytest runs tests with the project root in the Python path, so import mypackage.utils works. The function returns 42, so the assertion passes.

❓ assertion

advanced

Correct assertion for test package content

You want to write a pytest test to check that the tests package contains exactly 3 test files named test_*.py. Which assertion correctly verifies this?

PyTest

import os

def test_number_of_test_files():
    test_dir = os.path.join(os.path.dirname(__file__), '..', 'tests')
    test_files = [f for f in os.listdir(test_dir) if f.startswith('test_') and f.endswith('.py')]
    # Which assertion is correct here?

A assert test_files == 3

B assert test_files.length == 3

C assert len(test_files) == 3

D assert len(test_files) > 3

💡 Hint

Use len() to get the number of items in a list.

len(test_files) returns the number of test files. Comparing it to 3 with == checks for exactly 3 files. Other options are invalid syntax or wrong logic.

🔧 Debug

advanced

Debugging pytest test package import error

You have this structure:

project_root/
  app/
    __init__.py
    module.py
  tests/
    test_module.py

In test_module.py, you write import app.module but get ModuleNotFoundError when running pytest. What is the most likely cause?

A You ran pytest from inside the tests directory instead of project_root

B You forgot to add __init__.py in the tests directory

C module.py has syntax errors preventing import

D pytest does not support imports from sibling packages

💡 Hint

pytest uses the current working directory to set the Python path.

Running pytest from inside the tests directory means the parent directory (project_root) is not in sys.path, so import app.module fails. Running pytest from project_root fixes this.

❓ framework

expert

Configuring pytest to recognize a test package outside default locations

You have a test package located at project_root/integration_tests/ which contains test files. By default, pytest does not discover tests there. Which configuration change will make pytest discover tests in integration_tests?

A Run pytest with <code>pytest -k integration_tests</code>

B Add a pytest.ini file with <code>[pytest]\ntestpaths = integration_tests</code>

C Rename integration_tests to tests and add __init__.py

D Add __init__.py to integration_tests and run pytest normally

💡 Hint

pytest.ini can specify directories to search for tests.

Adding testpaths = integration_tests in pytest.ini tells pytest to look in that directory for tests. Renaming or adding __init__.py alone does not change discovery paths. The -k option filters tests by name but does not add directories.