1. PyTest Not Discovering Tests

Understanding the Issue

PyTest fails to detect and execute test cases, returning a "no tests collected" message.

Root Causes

• Incorrect test function or class naming conventions.
• Missing __init__.py in test directories.
• Using non-standard test locations.

Fix

Ensure test files and functions follow PyTest naming conventions:

test_my_module.py

def test_function():
    assert True

Add __init__.py to test directories if necessary:

touch tests/__init__.py

Manually specify the test directory:

pytest tests/

2. Import Errors in PyTest

Understanding the Issue

Tests fail due to import errors when referencing application modules.

Root Causes

• Incorrect Python path settings.
• Missing or improperly installed dependencies.
• Conflicts between system and virtual environment packages.

Fix

Ensure the application path is added to sys.path:

import sys
sys.path.append("./src")

Use a virtual environment and install required packages:

python -m venv venv
source venv/bin/activate
pip install -r requirements.txt

Run tests from the root directory to avoid path issues:

pytest

3. PyTest Fixtures Not Executing

Understanding the Issue

Fixture functions do not execute or fail with unexpected errors.

Root Causes

• Incorrect fixture scope or missing decorator.
• Misconfigured fixture dependency injection.
• Using fixtures in test parameters instead of function arguments.

Fix

Define and correctly use fixture decorators:

import pytest

@pytest.fixture
def sample_fixture():
    return "sample data"

def test_example(sample_fixture):
    assert sample_fixture == "sample data"

Ensure correct fixture scope is used:

@pytest.fixture(scope="module")

Check fixture dependency injection:

def test_func(sample_fixture):
    assert sample_fixture is not None

4. Parameterized Tests Not Running

Understanding the Issue

PyTest does not execute parameterized test cases as expected.

Root Causes

• Incorrect @pytest.mark.parametrize syntax.
• Misconfigured parameter values.
• Using incompatible data types in test parameters.

Fix

Ensure correct parameterized test syntax:

@pytest.mark.parametrize("input,expected", [(2, 4), (3, 9)])
def test_square(input, expected):
    assert input * input == expected

Verify parameterized values are properly formatted:

[("a", "b"), ("c", "d")]

Run tests explicitly to verify execution:

pytest -v test_file.py

5. PyTest Integration Issues in CI/CD

Understanding the Issue

PyTest tests may fail or not execute properly in CI/CD pipelines.

Root Causes

• Missing dependencies in the CI environment.
• Incorrect test discovery path in CI configurations.
• Permissions issues preventing test execution.

Fix

Ensure dependencies are installed in the CI pipeline:

pip install -r requirements.txt

Specify the test path explicitly in the CI script:

pytest tests/

Use proper user permissions in the CI environment:

chmod +x run_tests.sh

Conclusion

PyTest is a powerful testing framework, but troubleshooting test discovery issues, import errors, fixture execution failures, parameterized test problems, and CI/CD integration errors is essential for reliable test automation. By following best practices in test organization, dependency management, and execution, developers can ensure seamless testing workflows.

FAQs

1. Why is PyTest not discovering my tests?

Ensure test files and functions follow PyTest naming conventions, and add __init__.py to test directories.

2. How do I fix import errors in PyTest?

Check Python paths, use virtual environments, and ensure dependencies are installed correctly.

3. Why are my PyTest fixtures not running?

Verify fixture decorators, check dependency injection, and use correct fixture scope.

4. How do I fix parameterized tests not running?

Ensure correct @pytest.mark.parametrize syntax and verify test data format.

5. How do I troubleshoot PyTest failures in CI/CD?

Install dependencies, specify test paths explicitly, and ensure correct permissions.