Test classes in PyTest - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of pytest test class with setup method

What is the output when running this pytest test class?

PyTest

import pytest

class TestExample:
    def setup_method(self):
        self.value = 5

    def test_add(self):
        assert self.value + 3 == 8

    def test_subtract(self):
        assert self.value - 2 == 3

A Both tests fail

B test_add passes, test_subtract fails

C test_add fails, test_subtract passes

D Both tests pass

💡 Hint

setup_method runs before each test method to set self.value

The setup_method sets self.value to 5 before each test. test_add checks 5 + 3 == 8 which is True. test_subtract checks 5 - 2 == 3 which is True. So both tests pass.

❓ assertion

intermediate

Correct assertion to check list length in test class

Which assertion correctly checks that the list has exactly 4 items inside a pytest test method?

PyTest

class TestList:
    def test_length(self):
        items = [1, 2, 3, 4]

A assert items.count == 4

B assert items.length == 4

C assert len(items) == 4

D assert items.size() == 4

💡 Hint

Use Python's built-in function to get length of a list

len(items) returns the number of elements in the list. The other options use invalid syntax or methods not available on Python lists.

🔧 Debug

advanced

Identify the error in this pytest test class

What error will occur when running this pytest test class?

PyTest

class TestCalc:
    def setup(self):
        self.num = 10

    def test_multiply(self):
        assert self.num * 2 == 20

A AttributeError: 'TestCalc' object has no attribute 'num'

B AssertionError because 10 * 2 != 20

C No error, test passes

D SyntaxError due to missing colon

💡 Hint

Check if the setup method is named correctly for pytest

pytest expects setup_method(self) or setup_class(cls) for setup. The method named setup(self) is ignored, so self.num is never set. Accessing self.num causes AttributeError.

❓ framework

advanced

Best practice for sharing setup code in pytest test classes

Which approach is best to share setup code for all test methods in a pytest test class?

A Use a setup_method(self) to initialize instance variables before each test

B Define variables directly inside each test method

C Use __init__(self) method to initialize variables

D Use global variables outside the test class

💡 Hint

pytest calls setup_method automatically before each test method

setup_method(self) is the pytest convention to run setup code before each test method. __init__ is not recommended because pytest creates new instances differently. Defining variables inside each test repeats code. Global variables reduce test isolation.

🧠 Conceptual

expert

Why use test classes in pytest instead of standalone test functions?

What is the main advantage of organizing tests inside classes in pytest?

A To make tests run faster by parallel execution

B To group related tests and share setup/teardown code easily

C To avoid writing assert statements in tests

D To automatically generate test reports without configuration

💡 Hint

Think about code reuse and organization

Test classes help group related tests logically and allow sharing setup and teardown code via methods like setup_method. This improves code organization and reduces duplication. Other options are incorrect because classes do not affect speed, assert statements are always needed, and reports require separate configuration.