Junit | Test Automation Tools | Automatedtesting Tutorial

What is JUnit?

JUnit is a unit testing framework for Java programming language. It is an open-source framework that allows developers to write and run repeatable tests. JUnit is an essential part of test-driven development (TDD) in Java and is widely used for testing Java applications.

Setting Up JUnit

To get started with JUnit, you need to include it in your Java project. You can do this by adding the JUnit library to your project dependencies. If you are using Maven, you can add the following dependency to your pom.xml:

<dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.13.2</version>
    <scope>test</scope>
</dependency>

If you are not using Maven, you can download the JUnit jar files and add them to your project’s build path manually.

Creating Your First Test Case

Once JUnit is set up, you can create your first test case. A test case is a method that tests a small part of your application. Here is an example of a simple test case:

import org.junit.Test;
import static org.junit.Assert.assertEquals;

public class CalculatorTest {
    @Test
    public void testAddition() {
        Calculator calculator = new Calculator();
        assertEquals(5, calculator.add(2, 3));
    }
}

In this example, we are testing a method called add from a Calculator class. The @Test annotation tells JUnit that this is a test method.

Running Your Tests

To run your tests, you can use your IDE's built-in JUnit support or run them from the command line using Maven. If you are using Maven, you can run the following command in your project directory:

mvn test

This command will compile your code and run all the tests in your project. You will see the results in the command line or in your IDE.

Assertions in JUnit

Assertions are used to test whether the expected outcome matches the actual outcome. JUnit provides several assertion methods, such as:

assertEquals(expected, actual)
assertTrue(condition)
assertFalse(condition)
assertNull(object)
assertNotNull(object)

Here is an example of using multiple assertions:

@Test
public void testAssertions() {
    assertEquals(4, 2 + 2);
    assertTrue(true);
    assertFalse(false);
    assertNotNull(new Object());
}

JUnit Annotations

JUnit uses annotations to identify test methods and to perform setup and teardown operations. Here are some commonly used annotations:

@Before: Runs before each test method.
@After: Runs after each test method.
@BeforeClass: Runs once before any test methods in the class.
@AfterClass: Runs once after all test methods in the class.
@Ignore: Ignores a test method.

Example of using @Before and @After:

@Before
public void setUp() {
    // Code to set up before each test
}

@After
public void tearDown() {
    // Code to clean up after each test
}

Conclusion

JUnit is a powerful framework for unit testing in Java. It helps developers ensure their code works as expected and facilitates test-driven development. By following this tutorial, you should now have a good understanding of how to set up JUnit, create test cases, use assertions, and leverage annotations effectively.

JUnit Tutorial