Unit Tests and Where to Use Them

Unit tests are a type of automated software testing that focuses on verifying the correctness of individual, isolated units of code within a software application. These units typically represent the smallest testable parts of the codebase, such as functions, methods, and classes. The main characteristics of unit tests are as follows:

• Isolation: Unit tests are designed to isolate the specific unit of code being tested from the rest of the application. This isolation is often achieved by using techniques like mocking or stubbing to simulate the behavior of dependencies external to the module being tested.

• Independence: Unit tests should be independent of each other, meaning the outcome of one test should not affect the results of another. This allows tests to be run in any order and helps pinpoint the exact location of issues when tests fail.

• Deterministic: Unit tests produce deterministic results, meaning that they always produce the same output for a given set of inputs. This predictability is crucial for identifying and fixing defects.

• Focused scope: Each unit test focuses on a specific aspect or behavior of the unit of code being tested. It typically tests one piece of functionality or one use case.

• Fast execution: Unit tests are expected to execute quickly, making them suitable for running frequently during development. Fast feedback helps catch and address issues early in the development process.

• Automated: Unit tests are automated, meaning they are written as code and can be executed automatically using testing frameworks and tools. This automation ensures consistency and repeatability in the testing process.

Setting up unit tests in xUnit

As the name suggests, xUnit is primarily designed for unit testing. The following playground demonstrates how unit tests are typically set up: