Test classes in PyTest

Introduction

Test classes help organize related tests together. They make tests easier to read and manage.

When you have multiple tests for the same feature or function.

When you want to share setup steps for several tests.

When grouping tests by functionality or module improves clarity.

When you want to reuse code like setup or helper methods across tests.

Syntax

PyTest

class TestClassName:
    def test_method1(self):
        assert condition

    def test_method2(self):
        assert condition

Test classes must start with 'Test' for pytest to find them automatically.

Test methods inside must start with 'test_' to be recognized as tests.

Examples

A simple test class with one test method checking addition.

PyTest

class TestMath:
    def test_add(self):
        assert 1 + 1 == 2

Test class with two tests for string methods.

PyTest

class TestStrings:
    def test_upper(self):
        assert 'hello'.upper() == 'HELLO'

    def test_isupper(self):
        assert 'HELLO'.isupper()

Sample Program

This test class groups two simple math tests. Both tests check basic math operations.

PyTest

class TestCalculator:
    def test_add(self):
        assert 2 + 3 == 5

    def test_subtract(self):
        assert 5 - 3 == 2

Important Notes

Use test classes to keep tests organized and avoid repeating setup code.

Do not add an __init__ method to test classes; pytest creates instances automatically.

Use setup_method(self) if you need to run code before each test method.

Summary

Test classes group related tests for better organization.

Class names must start with 'Test' and methods with 'test_'.

They help share setup and keep tests clean and readable.