Application
Programming
Hend Alkittawi

Testing
Introduction to JUnit Framework for
Testing Java Code

INTRODUCTION

-

Testing in application programming/software development
Image Source: https://commons.wikimedia.org/wiki/File:SDLC_-_Software_Development_Life_Cycle.jpg

INTRODUCTION
-

Unit testing is a software testing method where individual
components of a software application, known as "units", are
tested in isolation from the rest of the application.

-

A unit is typically the smallest testable part of an
application, such as a function, method, or class.

-

Unit tests are designed to validate that each unit of the
software performs as expected. These tests are usually
automated and are written and run by software developers as
part of the development process.

UNIT TESTING
-

Unit testing is a systematic attempt to reveal errors

I DON’T ALWAYS TEST
CODE
BUT WHEN I DO, I DO IT
IN PRODUCTION

��

UNIT TESTING
-

Importance of Unit Testing in Software Development
-

Early Detection of Issues

-

Improved Code Quality

-

Reduces Debugging Time

-

Promotes Confidence and Reliability

-

Cost Efficiency

-

Supports Continuous Integration and Continuous Deployment

-

Documentation

UNIT TESTING
-

For each method implemented, consider the following when
creating the test cases
-

Preconditions: Assumptions/requirements made on the parameters
or class variables to be used in the method.

-

Postconditions: Assumptions/requirements made on the returned
value (or updated class variables) at the end of the method.

JUNIT TESTING
-

JUnit is a widely used open-source testing framework for Java
programming language. It provides an easy-to-use framework for
writing and running repeatable tests.

-

JUnit has become the de facto standard for unit testing in
Java, integrated with various development environments and
build tools.

-

JUnit is linked as a JAR at compile-time

-

The framework resides under package org.junit

JUNIT TESTING
-

JUnit uses Java annotations to define test methods and manage
test life cycle events. Key annotations include:
-

@Test: Marks a method as a test method.

-

@Before: Runs before each test method to perform setup.

-

@After: Runs after each test method to perform cleanup.

-

@BeforeClass: Runs once before any of the test methods in the
class.

-

@AfterClass: Runs once after all the test methods in the
class.

-

@Ignore: Ignores the marked test method.

JUNIT ANNOTATIONS

JUNIT TESTING
-

JUnit provides a set of assertion methods to verify expected
outcomes, such as:
-

assertEquals(expected, actual)

-

assertNotEquals(unexpected, actual)

-

assertTrue(condition)

-

assertFalse(condition)

-

assertNull(object)

-

assertNotNull(object)

-

fail(message)

JUNIT IN ECLIPSE
-

JUnit integrates seamlessly with IDEs like Eclipse

-

To create a JUnit test in Eclipse
-

Create a new package, name it test, under your project (New >
Package)

-

Right-click on the test package > New JUnit Test Case

-

On the New JUnit Test Case wizard, select JUnit 4 and fill the
fields

-

Select which methods to be tested in the generated class

-

Add the JUnit library to the build path

-

Create the test methods and run the test

Create a new package under your project (New > Package)

Right-click on the test package > New JUnit Test Case

On the New JUnit Test Case wizard, select JUnit 4 and fill the highlighted
fields > Next

Select which methods are to be tested in the generated class > Finish

Add the JUnit library to the build path

Create the test methods and run the test
right-click in the text editor > Run As > JUint Test

package core;

package test;

public class StringUtils {

public class TestStringUtils {

public static String capitalize(String input) {
return input.toUpperCase();
}

@Ignore
public void testCapitalize() {
fail("Not yet implemented");
}

public static boolean isPalindrome(String str) {
if (str == null)
throw new IllegalArgumentException("Input string cannot be null");

@Test
public void testIsPalindromePalindromeString() {
boolean result = StringUtils.isPalindrome("racecar");
assertTrue(result);
}

str = str.toLowerCase();
int left = 0;
int right = str.length() - 1;
while (left < right) {
if (str.charAt(left++) != str.charAt(right--)) {
return false;
}
}
return true;
}
}

@Test
public void testIsPalindromeNonPalindromeString() {
boolean result = StringUtils.isPalindrome("hello");
assertFalse(result);
}
}

package core;

package test;

public class Calculator {

public class TestCalculator {

public int add(int a, int b) {
return a + b;
}

private Calculator calculator;
@Before
public void setUp() {
calculator = new Calculator();
}

public int subtract(int a, int b) {
return a - b;
}

@Test
public void testAdd() {
assertEquals(5, calculator.add(2, 3));
assertEquals(-1, calculator.add(2, -3));
assertEquals(0, calculator.add(0, 0));
}

public int multiply(int a, int b) {
return a * b;
}
public int divide(int a, int b) {
if (b == 0)
throw new IllegalArgumentException("Cannot divide by zero");
return a / b;
}

@Test
public void testSubtract() {
fail("Not yet implemented");
}

}

@Test
public void testDivide() {
assertEquals(2, calculator.divide(6, 3));
assertEquals(-2, calculator.divide(-6, 3));
assertEquals(0, calculator.divide(0, 5));
}
@Test(expected = IllegalArgumentException.class)
public void testDivisionByZero() {
calculator.divide(10, 0);
}
}

package core;

package test;

public class Car {

public class TestCar {

private String make;
private String model;
private int year;
private double fuelLevel;

@Test
public void testAddFuel() {
Car car = new Car("Toyota", "Camry", 2022);
car.addFuel(20.0);
assertEquals(20.0, car.getFuelLevel(), 0.0);
}

public Car(String make, String model, int year) {
this.make = make;
this.model = model;
this.year = year;
this.fuelLevel = 0.0;
}

@Test
public void testDriveWithEnoughFuel() {
Car car = new Car("Honda", "Accord", 2023);
car.addFuel(30.0);
car.drive(150.0); // Assuming 150 miles drive
assertEquals(15.0, car.getFuelLevel(), 0.0);
}

// getters, setters, and other methods
public void drive(double distance) {
if (fuelLevel > 0) {
fuelLevel -= distance / 10; // Assuming fuel consumption
// rate of 10 units per mile
}
}

@Test
public void testDriveWithInsufficientFuel() {
Car car = new Car("Ford", "Focus", 2021);
car.addFuel(10.0);
car.drive(150.0); // Assuming 150 miles drive
assertEquals(10.0, car.getFuelLevel(), 0.0);
}

}
}

CODE DEMO
-

Show how to create and
run JUnit tests in
Eclipse.

DO YOU HAVE ANY
QUESTIONS?

THANK
YOU!

@

hend.alkittawi@utsa.edu

By Appointment
Online