Section 9: Testing in Java

Lesson 1: Unit Testing with JUnit

1.1 Introduction to Unit Testing

Understanding the importance of unit testing in software development.

Benefits of unit testing in terms of code reliability and maintainability.

1.2 Getting Started with JUnit

Overview of JUnit, a popular unit testing framework for Java.

Integrating JUnit into Java projects using build tools like Maven or Gradle.

Lesson 2: Writing and Executing Tests in Java

2.1 Writing JUnit Test Cases

Creating test classes and methods using JUnit annotations.

Writing test cases to verify the correctness of individual units of code.

Example (JUnit Test Case):

import static org.junit.jupiter.api.Assertions.*;

import org.junit.jupiter.api.Test;

public class MyMathTest {

    @Test

    public void testAddition() {

        MyMath math = new MyMath();

        int result = math.add(2, 3);

        assertEquals(5, result);

    }

    @Test

    public void testSubtraction() {

        MyMath math = new MyMath();

        int result = math.subtract(5, 3);

        assertEquals(2, result);

    }

}

2.2 Executing JUnit Tests

Running JUnit tests using IDEs or build tools.

Analyzing test results and interpreting feedback.

Lesson 3: Test-Driven Development (TDD) Principles

3.1 Understanding Test-Driven Development

Overview of the Test-Driven Development (TDD) methodology.

The TDD cycle: Red, Green, Refactor.

3.2 Applying TDD in Java

Writing tests before implementing code.

Iterative development and continuous testing.

Example (TDD Workflow):

• Write a failing test.

• Implement the minimum code to make the test pass.

• Refactor the code for clarity and maintainability.

import static org.junit.jupiter.api.Assertions.*;

import org.junit.jupiter.api.Test;

public class CalculatorTest {

    @Test

    public void testAddition() {

        Calculator calculator = new Calculator();

        assertEquals(5, calculator.add(2, 3));

    }

    @Test

    public void testSubtraction() {

        Calculator calculator = new Calculator();

        assertEquals(2, calculator.subtract(5, 3));

    }

}

Testing is a crucial aspect of software development, ensuring that code functions as intended and remains robust during changes. Embracing unit testing with JUnit and incorporating Test-Driven Development principles contributes to the overall quality of Java applications. Practice writing and executing tests to reinforce your understanding of testing in Java.