Fixture composition in PyTest - Test Execution Trace

Test Overview

This test uses pytest fixtures where one fixture uses another fixture to prepare test data. It verifies that the composed fixtures work together to provide the correct final value.

Test Code - pytest

PyTest

import pytest

@pytest.fixture
def base_number():
    return 5

@pytest.fixture
def multiplied_number(base_number):
    return base_number * 3

def test_composed_fixture(multiplied_number):
    assert multiplied_number == 15

Execution Trace - 6 Steps

Step	Action	System State	Assertion	Result
1	Test starts	pytest test runner initialized	-	PASS
2	pytest collects test_composed_fixture and its fixtures	Fixtures base_number and multiplied_number recognized	-	PASS
3	pytest calls base_number fixture	base_number returns 5	-	PASS
4	pytest calls multiplied_number fixture with base_number value	multiplied_number returns 15 (5 * 3)	-	PASS
5	pytest runs test_composed_fixture with multiplied_number value	test_composed_fixture receives 15	assert multiplied_number == 15	PASS
6	Test ends successfully	Test passed with no errors	-	PASS

Failure Scenario

Failing Condition: multiplied_number fixture returns incorrect value

Execution Trace Quiz - 3 Questions

Which fixture provides the initial number used in the test?

A base_number

B multiplied_number

C test_composed_fixture

D pytest

Key Result

Using fixture composition helps organize test setup by building complex data from simple fixtures, making tests easier to maintain and reuse.