What Is JUnit: An Overview of the Best Java Testing Framework

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Introduction

JUnit is a Java unit testing framework and one of the most suitable test approaches for regression testing. As an open-source framework that reports and operates repeatable automated trials and the JUnit testing framework has evolved. Since JUnit is consistent with nearly all IDEs, associations worldwide have embraced it to execute unit testing in the Java Programming Language. In Java, test cases need to re-execute every while an unknown code adds. It is to ensure that nothing in the code is an error. JUnit plays a significant part when it arrives at regression testing. Regression Testing is software testing that examines if the current modifications made to the code do not adversely influence the earlier written code.

What is the Need for JUnit Testing?

Unit testing is a software testing technique where units (the unique parts of software) experiment. Developers register unit tests for their code to ensure the code functions accurately. It allows us to detect and guard against bugs in the future. The primary purpose of JUnit Testing is to find bugs earlier in the development stage and improves the code's reliability. The framework enables the developer to invest more while reading the code than noting it. It constructs the code more readable, dependable, and bug-free. It increases the spirit of the developer and encourages them greatly. JUnit is elegantly straightforward and is slightly tricky, and takes less time. JUnit tests operate automatically, review their results and provide instant feedback. There is no requirement for a manual report of test results.

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Features of JUnit

Some features of JUnit Testing in Java:-

• Open Source Network: JUnit is an open-source web that allows developers to write codes quickly and with more pleasing standards.
• Annotations: It produces several annotations to specify test techniques.
• Assertions: There are assertions to test desired developments.
• Test Runners: JUnit has test runners to execute tests.
• Code Quality: JUnit is the most widespread Testing Framework for better testing. It permits more rapid code writing, which improves the code’s quality. 
• Automated Test Running: The test outcomes do not demand manual checking. All the tests operate automatically on JUnit, the results acquired likewise are automatically checked, and it delivers feedback.
• Interpretable Results: The test results are presented in a line showing test improvement, thus making them efficiently interpretable.

What are JUnit Annotations?

JUnit Annotations are a notable format of syntactic meta-data that adds to Java source code for more useful code readability and arrangement. Packages, classes, variables, methods, and parameters can be annotated. Annotations were introduced in Junit4, which makes Java code better readable and easy.

Such JUnit annotations used in Java are:-

1. @Test This annotation is a substitute for org.JUnit.TestCase indicates the public void process to which it is connected and managed as a Test Case.

2. @Before This annotation executes some declarations like preconditions before every test case.

3. @BeforeClass This annotation is conducted if you want to run some statements before all the test cases, e.g. test connection performs before all the test cases.

4. @After This annotation operates some statements after each test case, e.g resetting variables, deleting momentary files, variables, etc.

5. @AfterClass This annotation is used to execute some statements after all test cases, e.g. Emitting resources after operating all test cases.

6. @Ignores This annotation ignores some remarks during test execution, e.g. disabling some test cases during the test execution.

7. @Test(timeout=500) This annotation is used to arrange some timeout during test implementation, e.g. if you are operating under some SLA (Service level agreement) and tests need to be achieved within some specified span.

8. @Test(expected=IllegalArgumentException.class) This annotation handles some exceptions during test execution. E.g., if you like to inspect whether a particular method throws a specified exception.

JUnit Annotations Example with code

Let’s make a class surrounding significant JUnit annotations with easy print statements and run it with a test runner class

import static org.junit.Assert.assertEquals;

import static org.junit.Assert.assertFalse;

import java.util.ArrayList;

import org.junit.After;

import org.junit.AfterClass;

import org.junit.Before;

import org.junit.BeforeClass;

import org.junit.Ignore;

import org.junit.Test;

public class JunitAnnotationsExample

 {

    private ArrayList list;

    @BeforeClass

    public static void mark1() {

        System.out.print("Using @BeforeClass , run before all test cases ");

    }

    @Before

    public void mark2() 

{

        list = new ArrayList();

        System.out.print("Using @Before annotations ,executed before each test cases ");

    }

    @AfterClass

    public static void mark3() 

{

        System.out.print("Using @AfterClass ,executed after all test cases");

    }

    @After

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