Context manager fixtures in PyTest - Build an Automation Script

Test resource setup and cleanup using a context manager fixture

Preconditions (2)

Step 1: Create a pytest fixture using the @pytest.fixture decorator with yield to act as a context manager

Step 2: In the fixture, set up a resource before the yield statement

Step 3: After the yield statement, clean up the resource

Step 4: Write a test function that uses this fixture as a parameter

Step 5: Inside the test, verify the resource is set up correctly

Step 6: Run the test using pytest

✅ Expected Result: The test passes, confirming the resource was set up before the test and cleaned up after the test

Automation Requirements - pytest

Assertions Needed:

Assert the resource is correctly set up before test execution

Assert the cleanup code runs after the test

Best Practices:

Use yield in fixtures to separate setup and teardown

Keep fixture scope appropriate (function scope by default)

Use clear and descriptive fixture names

Automated Solution

PyTest

import pytest

@pytest.fixture
def resource():
    # Setup code
    data = {'status': 'initialized'}
    print('Setup resource')
    yield data
    # Teardown code
    data['status'] = 'cleaned'
    print('Cleanup resource')


def test_resource_usage(resource):
    # Assert resource is set up
    assert resource['status'] == 'initialized'
    # Simulate test actions
    resource['status'] = 'used'
    assert resource['status'] == 'used'

The fixture resource uses yield to separate setup and teardown. Before yield, it initializes a dictionary to simulate a resource and prints a setup message. After yield, it modifies the dictionary to indicate cleanup and prints a cleanup message.

The test function test_resource_usage receives the fixture as a parameter. It asserts the resource is initialized before use, modifies it to simulate usage, and asserts the change.

When running with pytest, the setup code runs before the test, and the teardown code runs after, ensuring proper resource management.

Common Mistakes - 3 Pitfalls

Not using yield in fixture and placing teardown code after return

Using print statements instead of assertions to verify setup

Using global variables inside fixture without proper isolation

Bonus Challenge

Now add data-driven testing with 3 different resource initial states using the context manager fixture

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