If you are a developer or develop something, even a small program, then you might need to test it before releasing it to production, and from my experience, testing is literally a hectic task even for the experienced ones. Many enterprise applications are developed using Java because of its high portability, scalability and security. So in this blog, we will introduce you to one of the most popular and useful framework for Java developers, i.e., JUnit, which is developed to work in test-driven environments.
First, let’s understand the need for testing.
Suppose you are working on a project and initially it has few functions, then testing of each function and the whole project is easier. If some error might occur, you may check the individual function’s implementation to rectify the error. But as the functionality of the project increases, think of an enterprise application like YouTube, Paytm, they might contain thousands of functions, and it is impossible to test such an application function-by-function. There might be several reasons for it:
- Does the new function has an error?
- Which kind of input is producing the error?
- How to detect and rectify the error?
For testing, test cases are prepared which have particular output on each input case. Testing ensures the correctness of the application. If the function passes the test cases, then it is bug-free otherwise, not. Manual testing for small applications is possible, but for enterprise applications, test cases are also huge, so we need some automation testing tool that automatically tests the application whenever the application’s functionality changes.
Java developers use JUnit for automated testing. It is a unit testing framework used for writing and running repeatable tests. Whenever project functionality modifies, it must pass all the test cases to ensure nothing is broken, which JUnit makes easier. JUnit finds the bugs in the early stages of development and makes the code more readable, reliable, and bug-free.
We are going to use the latest version of JUnit, i.e., JUnit5. Java 8 is the minimum requirement for JUnit5 and the higher version. It comprises several discrete components:
JUnit5 = JUnit Platform + JUnit Jupiter + JUnit Vintage
i) JUnit Platform :
It is a foundation layer that enables different testing frameworks to be launch over the JVM. For developing the testing frameworks that run on the JUnit platform, it defines the TestEngine API, which also enables you to use 3rd party testing libraries directly into JUnit by implementing its custom TestEngine.
ii) JUnit Jupiter:
It is a new programming and extension model for writing unit tests in JUnit 5 and an extension for JUnit 4.
iii) JUnit Vintage:
A TestEngine to support tests based on JUnit3 and JUnit 4 on JUnit 5.
Now you have understood why testing is necessary and what is JUnit? So it’s time to move ahead to JUnit5 installation.
You can set up JUnit5 to either download all the 3 jar files and include them into the project or by using maven. Here is the pretty straightforward way by including the JUnit dependencies into the pom.xml.
<dependency> <groupId>org.junit.jupiter</groupId> <artifactId>junit-jupiter-engine</artifactId> <version>5.1.0</version> <scope>test</scope> </dependency>
JUnit5 or above versions require Java 8.
JUnit is a powerful framework that boosts your development speed and lets you focus more on development instead of testing. I hope the above write-up was enough for you to get familiar with JUnit5. Further in this series, we will cover annotations in JUnit and create Test Suites, Exception Testing, Assertions, and Assumptions.