Given-When-Then pattern in PyTest - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this pytest Given-When-Then test?

Consider this pytest test using the Given-When-Then pattern. What will be the test result?

PyTest

import pytest

def add(a, b):
    return a + b

def test_addition():
    # Given two numbers
    x = 3
    y = 4

    # When they are added
    result = add(x, y)

    # Then the result should be 7
    assert result == 7

A Test passes successfully

B Test fails with AssertionError

C Test raises a NameError

D Test raises a TypeError

💡 Hint

Check the add function and the assertion carefully.

The add function correctly sums 3 and 4 to 7. The assertion checks if result == 7, which is true, so the test passes.

❓ assertion

intermediate

Which assertion correctly follows the Then step in Given-When-Then?

You want to check that a function returns a list with exactly 3 items. Which assertion fits the Then step best?

A assert result is not None

B assert len(result) == 3

C assert result[0] == 3

D assert type(result) == dict

💡 Hint

Focus on checking the number of items in the list.

The Then step verifies the expected outcome. Checking length equals 3 confirms the list size is correct.

🔧 Debug

advanced

Why does this Given-When-Then test fail?

This pytest test using Given-When-Then fails. What is the cause?

PyTest

def multiply(a, b):
    return a * b

def test_multiply():
    # Given two numbers
    x = 2
    y = 5

    # When they are multiplied
    result = multiply(x, y)

    # Then the result should be 15
    assert result == 15

A The assertion syntax is invalid

B The multiply function has a syntax error

C The variables x and y are not defined

D The expected result in Then step is incorrect

💡 Hint

Calculate 2 times 5 and compare with the expected result.

2 multiplied by 5 equals 10, but the test expects 15, so the assertion fails.

🧠 Conceptual

advanced

What is the main purpose of the Given-When-Then pattern in testing?

Choose the best description of the Given-When-Then pattern's purpose.

A To write tests that run faster by skipping setup steps

B To replace all assertions with print statements

C To structure tests clearly by separating setup, action, and verification

D To avoid writing any code in the test functions

💡 Hint

Think about how tests are organized for clarity.

Given-When-Then helps organize tests into setup (Given), action (When), and check (Then) for readability and maintainability.

❓ framework

expert

Which pytest fixture usage best fits the Given step in Given-When-Then?

You want to prepare test data before running the test action. Which fixture usage fits the Given step best?

A

@pytest.fixture
def setup_data():
    return {'user': 'alice', 'age': 30}

# In test:
# def test_user(setup_data):
#     ...

B

@pytest.mark.parametrize('input', [1, 2, 3])
def test_numbers(input):
    ...

C

def test_action():
    result = do_something()
    assert result is True

D

@pytest.fixture
def teardown_data():
    print('Cleaning up')

💡 Hint

Given step prepares data or state before the action.

Fixture setup_data prepares test data before the test runs, matching the Given step role.