setup.cfg configuration in PyTest - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the setup.cfg file in pytest?

The setup.cfg file is used to configure pytest settings and options in a simple, declarative way without needing command-line arguments.

beginner

How do you specify the directory where pytest should look for tests in setup.cfg?

You can specify the test directory using the testpaths option under the [tool:pytest] section, for example:

[tool:pytest]
testpaths = tests

beginner

What section header is used in setup.cfg to configure pytest options?

The section header is [tool:pytest]. All pytest options go under this section.

intermediate

How can you add command-line options like --maxfail=2 and -v in setup.cfg?

Use the addopts option under [tool:pytest], for example:

[tool:pytest]
addopts = -v --maxfail=2

beginner

Why is using setup.cfg for pytest configuration better than passing options via command line every time?

It keeps configuration consistent and reusable across runs and team members, avoids mistakes from missing options, and makes automation easier.

Which section header is correct for pytest settings in setup.cfg?

A [pytest]

B [tool:pytest]

C [pytest-config]

D [tool:python]

The correct section header for pytest configuration in setup.cfg is [tool:pytest].

How do you tell pytest to look for tests in the tests folder using setup.cfg?

A tests_folder = tests

B testdir = tests

C testpaths = tests

D test_location = tests

The option testpaths specifies directories where pytest looks for tests.

What does the addopts option do in setup.cfg?

A Adds extra command-line options to pytest runs

B Specifies the test file extensions

C Defines the Python version to use

D Sets the test timeout duration

addopts lets you add command-line options like -v or --maxfail=2 in the config file.

If you want pytest to stop after 1 failure, how do you set this in setup.cfg?

A addopts = --maxfail=1

B maxfail = 1

C failfast = true

D stop_after_fail = 1

You use addopts = --maxfail=1 to tell pytest to stop after one failure.

Why might teams prefer setup.cfg over command-line options for pytest?

A It runs tests faster

B It disables all warnings

C It automatically fixes test failures

D It ensures consistent test settings for everyone

Using setup.cfg keeps test settings consistent and avoids forgetting options.

Explain how to configure pytest to run tests in a specific folder and add verbose output using setup.cfg.

Think about the section header and the two main options for paths and extra command-line flags.

Describe the benefits of using setup.cfg for pytest configuration instead of command-line arguments.

Consider how configuration files help teams and automation.

Practice

1. What is the main purpose of the setup.cfg file in pytest?

easy

A. To store pytest configuration settings in one place

B. To write test functions

C. To install pytest package

D. To run tests manually from the command line

Solution

1. Step 1: Understand pytest configuration

   The setup.cfg file is used to keep pytest settings centralized.

2. Step 2: Differentiate from other tasks

   Writing tests or installing packages are not roles of setup.cfg.

3. Final Answer:

   To store pytest configuration settings in one place -> Option A

4. Quick Check:

   setup.cfg centralizes pytest settings [OK]

Hint: Remember setup.cfg holds config, not test code [OK]

Common Mistakes:

• Confusing setup.cfg with test files
• Thinking setup.cfg runs tests
• Assuming setup.cfg installs packages

2. Which of the following is the correct way to specify the test file pattern in setup.cfg?

easy

A. [pytest]\ntestpaths = tests

B. [pytest]\npython_files = test_*.py

C. [tool:pytest]\npython_files = *.txt

D. [pytest]\nmarkers = test_*.py

Solution

1. Step 1: Identify correct section and key

   pytest settings go under [pytest] and python_files sets test file patterns.

2. Step 2: Check pattern correctness

   python_files = test_*.py matches typical test files.

3. Final Answer:

   [pytest]\npython_files = test_*.py -> Option B

4. Quick Check:

   python_files sets test file pattern [OK]

Hint: Use python_files to set test file patterns [OK]

Common Mistakes:

• Using wrong section header like [tool:pytest]
• Confusing markers with file patterns
• Setting testpaths instead of python_files for file pattern

3. Given this setup.cfg snippet:

[pytest]
markers = slow: marks tests as slow
python_files = test_*.py

What happens when you run pytest -m slow?

medium

A. Tests in files not matching test_*.py run

B. All tests run ignoring markers

C. Tests with names containing 'slow' run

D. Only tests marked with @pytest.mark.slow run

Solution

1. Step 1: Understand marker definition

   The marker slow is defined to label slow tests.

2. Step 2: Effect of -m slow option

   Running pytest -m slow runs only tests marked with @pytest.mark.slow.

3. Final Answer:

   Only tests marked with @pytest.mark.slow run -> Option D

4. Quick Check:

   -m runs tests with matching marker [OK]

Hint: -m runs tests with matching marker only [OK]

Common Mistakes:

• Thinking -m filters by test name
• Assuming all tests run ignoring markers
• Confusing file pattern with marker filtering

4. You added this to setup.cfg:

[pytest]
markers = slow: marks slow tests
python_files = test_*.py
python_classes = Test*
python_functions = test_*

But pytest gives a warning about unknown markers. What is the likely cause?

medium

A. Markers need to be registered with full description and no typos

B. Missing a blank line after [pytest] section

C. Markers must be listed under [tool:pytest] section

D. python_files setting conflicts with markers

Solution

1. Step 1: Check marker registration format

   Markers must be registered exactly with correct spelling and description.

2. Step 2: Understand warning cause

   Warnings usually occur if marker name is misspelled or description is missing.

3. Final Answer:

   Markers need to be registered with full description and no typos -> Option A

4. Quick Check:

   Correct marker registration avoids warnings [OK]

Hint: Check marker spelling and description carefully [OK]

Common Mistakes:

• Placing markers under wrong section
• Forgetting marker description after colon
• Assuming python_files affects markers

5. You want pytest to automatically ignore tests in the legacy_tests folder without typing command line options. How do you configure setup.cfg to do this?

hard

A. [pytest]
markers = ignore: skip legacy tests

B. [pytest]
python_files = test_*.py
ignore = legacy_tests

C. [pytest]
addopts = --ignore=legacy_tests

D. [pytest]
filterwarnings = ignore::legacy_tests

Solution

1. Step 1: Identify option to ignore folders

   The --ignore=folder option tells pytest to skip that folder.

2. Step 2: Set addopts in setup.cfg

   Adding addopts = --ignore=legacy_tests runs pytest with this option automatically.

3. Final Answer:

   [pytest]\naddopts = --ignore=legacy_tests -> Option C

4. Quick Check:

   addopts sets default command line options [OK]

Hint: Use addopts to add default command line options [OK]

Common Mistakes:

• Using ignore key instead of addopts
• Confusing markers with ignore settings
• Using filterwarnings incorrectly for ignoring tests