Fixture as function argument in PyTest - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of pytest fixture usage in test function

What is the output when running this pytest test function that uses a fixture as an argument?

PyTest

import pytest

@pytest.fixture
def sample_data():
    return [1, 2, 3]

def test_sum(sample_data):
    assert sum(sample_data) == 6
    print('Sum is:', sum(sample_data))

A Sum is: 6\nPASSED

B Sum is: 6\nFAILED

C TypeError: test_sum() missing 1 required positional argument: 'sample_data'

D NameError: name 'sample_data' is not defined

💡 Hint

Remember that pytest automatically injects fixtures by matching argument names.

The fixture 'sample_data' is passed automatically to the test function by pytest. The sum is 6, so the assertion passes and the print statement outputs 'Sum is: 6'.

❓ assertion

intermediate

Correct assertion using fixture data

Given a fixture that returns a dictionary, which assertion correctly verifies the value of key 'status' in the test function?

PyTest

import pytest

@pytest.fixture
def response():
    return {'status': 'ok', 'code': 200}

def test_response_status(response):
    # Which assertion is correct here?

A assert response['status'] != 'ok'

B assert response.status == 'ok'

C assert response.get('status') = 'ok'

D assert response['status'] == 'ok'

💡 Hint

Dictionaries use square brackets to access keys.

Option D correctly asserts that the value for key 'status' is 'ok'. Option D is invalid because dictionaries don't have attribute access. Option D uses assignment '=' instead of comparison '=='. Option D asserts the opposite of the correct condition.

🔧 Debug

advanced

Identify the error when fixture is not passed as argument

What error occurs when a test function tries to use a fixture variable without declaring it as a function argument?

PyTest

import pytest

@pytest.fixture
def data():
    return [10, 20, 30]

def test_data_sum():
    assert sum(data) == 60

A AssertionError: assert 60 == 60

B NameError: name 'data' is not defined

C TypeError: test_data_sum() missing 1 required positional argument: 'data'

D No error, test passes

💡 Hint

Fixtures must be declared as parameters to be injected.

The fixture 'data' is not passed as an argument, so the test function has no variable named 'data'. This causes a NameError.

❓ framework

advanced

How pytest discovers and injects fixtures

Which statement best describes how pytest uses fixtures as function arguments in tests?

A Pytest matches test function argument names to fixture names and injects the fixture return value automatically.

B Pytest requires manual import of fixtures inside each test function before use.

C Fixtures must be called inside the test function to get their values.

D Pytest only injects fixtures if they are decorated with @pytest.inject.

💡 Hint

Think about how pytest knows which fixture to use for each argument.

Pytest automatically injects fixtures by matching argument names to fixture functions. No manual import or calling is needed inside the test.

❓ locator

expert

Selecting the correct fixture usage pattern in pytest

Which of the following test function signatures correctly uses a fixture named 'db_connection' to ensure the fixture is injected?

A

def test_query():
    db_connection = db_connection()

B

def test_query():
    from fixtures import db_connection
    db_connection()

C def test_query(db_connection):

D def test_query(db_connection=None):

💡 Hint

Fixtures are injected by naming them as parameters without default values.

Option C correctly declares the fixture as a parameter. Option C tries to call the fixture like a function inside the test, which is incorrect. Option C manually imports and calls the fixture, which pytest does automatically. Option C sets a default None, so pytest will not inject the fixture.