jUnit - Unit tests in Java

To ensure the quality and functionality of our code, it is essential to make sure that the behaviors defined in our methods are working correctly. In this context, automated tests come into play, which can be classified into different categories, such as unit tests, integration tests and end-to-end tests (End-to-End). In this article, we will focus on unit testing.

Unit tests allow you to validate specific units of code, such as individual methods, ensuring that they behave as expected. In the Java ecosystem, the most used framework for this purpose is JUnit.

JUnit is a unit testing framework aimed at Java, with the aim of ensuring code quality by validating the correct functioning of each unit (usually methods). Next, we will see an example of a simple class, Calculator, which contains a sum method, responsible for performing the sum of two numbers. We will also present a unit test for this method, where we replicate the desired behavior to ensure the method is correct. To do this, we created the CalculatorTest class, which contains the automated test.

Currently, JUnit is in version 5, which has brought several improvements and new features. One of the main innovations is modularity, being divided into three main components:

JUnit Platform: Provide support for different execution environments.
JUnit Jupiter: Execution engine for the new JUnit 5 tests.
JUnit Vintage: Provides backwards compatible support for tests written in JUnit 3 and JUnit 4.
Additionally, JUnit 5 introduced native support for parameterized and dynamic tests, making it easier to run tests with different input values, as well as support for lambda expressions, taking advantage of modern Java features.

Unit tests play a fundamental role in maintaining code quality and robustness, especially in larger-scale projects where complexity increases. JUnit, being the main framework for unit testing in Java, has evolved significantly to meet modern development needs, offering greater flexibility, modularity and compatibility with new versions of Java. With the improvements brought by JUnit 5, it is possible to test code more efficiently, taking advantage of advanced features such as dynamic tests and lambda expressions, helping developers ensure that their methods work correctly in different scenarios.

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