Fixture teardown (yield) in PyTest - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of pytest fixture with yield

What will be the output when running this pytest test with the given fixture?

PyTest

import pytest

@pytest.fixture
def resource():
    print("Setup resource")
    yield "data"
    print("Teardown resource")

def test_example(resource):
    print(f"Using {resource}")
    assert resource == "data"

A Using data\nSetup resource\nTeardown resource

B Setup resource\nTeardown resource\nUsing data

C Setup resource\nUsing data\nTeardown resource

D Using data\nTeardown resource\nSetup resource

💡 Hint

Remember that code before yield runs before the test, and code after yield runs after the test.

The fixture runs setup code before yield, then the test runs using the yielded value, then teardown code runs after the test finishes.

❓ assertion

intermediate

Correct assertion for fixture teardown effect

Given a pytest fixture that yields a list and appends an item after yield, which assertion correctly verifies the list contents after the test?

PyTest

import pytest

@pytest.fixture
def my_list():
    data = []
    yield data
    data.append('done')

def test_modify_list(my_list):
    my_list.append('test')
    # Which assertion below correctly checks the list after test?

A assert my_list == ['done']

B assert my_list == ['test', 'done']

C assert my_list == []

D assert my_list == ['test']

💡 Hint

The assertion runs inside the test, before teardown code runs.

The teardown code runs after the test finishes, so inside the test the list only has 'test'. The 'done' item is appended after the test ends.

🔧 Debug

advanced

Identify the error in fixture teardown with yield

What error will this pytest fixture cause when used in a test?

PyTest

import pytest

@pytest.fixture
def broken_fixture():
    print("Setup")
    yield
    print("Teardown")
    yield

def test_broken(broken_fixture):
    assert True

A SyntaxError: multiple yield statements in fixture

B RuntimeError: generator didn't stop after second yield

C TypeError: fixture must yield exactly once

D No error, test passes normally

💡 Hint

A pytest fixture must yield exactly once; multiple yields cause runtime issues.

Pytest expects the fixture generator to yield once and then finish. Multiple yields cause a RuntimeError because the generator does not stop as expected.

🧠 Conceptual

advanced

Purpose of yield in pytest fixture teardown

Why does pytest use yield in fixtures for teardown instead of separate setup and teardown functions?

A Yield allows setup and teardown code to be in one place, improving readability and resource management.

B Yield makes the fixture run twice, once for setup and once for teardown.

C Yield is used to pause the test execution until teardown is manually triggered.

D Yield automatically retries the test if it fails during setup.

💡 Hint

Think about how yield separates setup and teardown in one function.

Using yield in fixtures lets you write setup code before yield and teardown code after yield in the same function, making tests cleaner and easier to maintain.

❓ framework

expert

Order of execution in multiple yield fixtures

Given two pytest fixtures using yield, what is the correct order of printed output when both are used in a test?

PyTest

import pytest

@pytest.fixture
def fixture_a():
    print("Setup A")
    yield
    print("Teardown A")

@pytest.fixture
def fixture_b():
    print("Setup B")
    yield
    print("Teardown B")

def test_both(fixture_a, fixture_b):
    print("Test running")
    assert True

A Setup A\nSetup B\nTest running\nTeardown B\nTeardown A

B Setup B\nSetup A\nTest running\nTeardown A\nTeardown B

C Setup B\nSetup A\nTest running\nTeardown B\nTeardown A

D Setup A\nSetup B\nTest running\nTeardown A\nTeardown B

💡 Hint

Fixtures are set up in order of parameters, but teardown happens in reverse order.

Pytest sets up fixtures in the order they appear in the test function parameters, then runs the test, then tears down fixtures in reverse order.