Unit Testing vs Functional Testing: Key Differences Explained

When building reliable software, testing is essential. But not all tests are created equal. Two of the most commonly used testing types are unit testing and functional testing . Though they may seem similar, they serve very different purposes in the software development lifecycle. In this guide, we’ll compare unit testing vs functional testing —highlighting what they are, how they differ, and when to use each. What Is Unit Testing? Unit testing is the process of testing individual units or components of a software application in isolation. A "unit" typically refers to a function, method, or class. The goal is to ensure that each part of the code works as expected on its own. Characteristics: Tests small, isolated pieces of code Fast to run and easy to automate Typically written by developers Uses mocks and stubs for dependencies Example: python CopyEdit def add(a, b): return a + b def test_add(): assert a...