Parametrize with indirect fixtures in PyTest - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of pytest test using indirect fixture parameterization

What will be the output of the following pytest test run?

Consider the test and fixture below:

PyTest

import pytest

@pytest.fixture
def data(request):
    return request.param * 2

@pytest.mark.parametrize('data', [1, 3, 5], indirect=True)
def test_double(data):
    assert data % 2 == 0
    print(f"Value: {data}")

A Test passes for all 3 inputs and prints: Value: 2, Value: 6, Value: 10

B Test fails on input 1 because 2 % 2 != 0

C Test fails on input 3 because 6 % 2 != 0

D Test fails on input 5 because 10 % 2 != 0

💡 Hint

Remember that the fixture multiplies the input by 2, making all outputs even.

The fixture 'data' receives the parameter via 'request.param' and returns it multiplied by 2. Since all inputs (1,3,5) multiplied by 2 are even numbers, the assertion 'data % 2 == 0' passes for all. The print statements show doubled values.

❓ assertion

intermediate

Correct assertion for indirect fixture parameter

Given this indirect fixture parameterization, which assertion correctly verifies the fixture output?

Code snippet:

import pytest

@pytest.fixture
def number(request):
    return request.param + 5

@pytest.mark.parametrize('number', [0, 2, 4], indirect=True)
def test_number(number):
    # Which assertion is correct here?
    pass

A assert number in [0, 2, 4]

B assert number in [5, 7, 9]

C assert number == request.param + 5

D assert number % 5 == 0

💡 Hint

The fixture adds 5 to each parameter value.

The fixture adds 5 to each parameter (0,2,4), so the expected outputs are 5,7,9. Option B correctly asserts this. Option B checks original params, C is invalid because 'request' is not defined in test, A is false because 7 and 9 are not divisible by 5.

🔧 Debug

advanced

Identify the error in indirect fixture usage

Why does this pytest test fail to run correctly?

Code:

import pytest

@pytest.fixture
def item(request):
    return request.param * 3

@pytest.mark.parametrize('item', [1, 2, 3])
def test_item(item):
    assert item % 3 == 0

A Fixture 'item' does not return a value

B Assertion is incorrect; item % 3 == 0 is always false

C Missing 'indirect=True' in parametrize causes 'request.param' to be undefined

D Parameter list must be strings, not integers

💡 Hint

Check how parameters are passed to fixtures when using indirect parameterization.

Without 'indirect=True', pytest passes the parameters directly to the test function, not the fixture. The fixture tries to access 'request.param' but 'request' is undefined, causing an error. Adding 'indirect=True' fixes this.

❓ framework

advanced

Best practice for complex indirect fixture parameterization

You want to test a function with multiple complex inputs using pytest indirect fixtures. Which approach is best?

Options:

A Use a single fixture that accepts a dictionary parameter and mark parametrize with indirect=True

B Use multiple fixtures each with separate parametrize decorators without indirect=True

C Pass all parameters directly to the test function without fixtures

D Use global variables to store test data and avoid fixtures

💡 Hint

Think about how to handle complex data cleanly and reuse fixture logic.

Using a single fixture that accepts a dictionary parameter allows clean handling of complex inputs. Marking parametrize with indirect=True passes the dictionary to the fixture for setup. Other options either avoid fixtures or misuse parametrize, reducing test clarity and reusability.

🧠 Conceptual

expert

Why use indirect parameterization in pytest fixtures?

Which statement best explains the purpose of using indirect parameterization with pytest fixtures?

A It converts test functions into fixtures for reuse.

B It automatically runs tests in parallel to speed up execution.

C It disables fixture caching to ensure fresh data for each test.

D It allows parameters to be passed to fixtures instead of directly to test functions, enabling setup logic based on parameters.

💡 Hint

Think about how indirect=True changes parameter passing behavior.

Indirect parameterization tells pytest to send parameters to the fixture, not the test function. This lets fixtures use parameters to prepare test data or setup. Other options describe unrelated pytest features.