testng Getting started with testng TestNG Hello World Example

Example

Writing and executing a simple TestNG program is mainly 3 step process.

1. Code - write business logic of your test and annotate it with TestNG annotations
2. Configure - add information of your test in testng.xml or in build.xml
3. Run TestNG - it can be invoked from command line, ANT, IDE like Eclipse, IntelliJ's IDEA)

Brief explanation of example (what needs to be tested):

We have a RandomNumberGenerator class which has a method generateFourDigitPin that generates a 4 digit PIN and returns as int. So here we want to test whether that random number is if of 4 digits or not. Below is the code:

Class to be tested:

package example.helloworld;

public class RandomNumberGenerator {

public int generateFourDigitPin(){
    return (int)(Math.random() * 10000);
}
}

The TestNG test class:

package example.helloworld;

import org.testng.Assert;
import org.testng.annotations.AfterClass;
import org.testng.annotations.BeforeClass;
import org.testng.annotations.Test;

public class TestRandomNumberGenerator {
    
    RandomNumberGenerator rng = null;
    
    @BeforeClass
    public void deSetup(){
        rng = new RandomNumberGenerator();
    }
    
    @Test
    public void testGenerateFourDigitPin(){
        int randomNumber = rng.generateFourDigitPin();
        Assert.assertEquals(4, String.valueOf(randomNumber).length());
    }
    
    @AfterClass
    public void doCleanup(){
        //cleanup stuff goes here
    }
}

Ther testng.xml:

<suite name="Hello World">
    <test name="Random Number Generator Test">
        <classes>
            <class name="example.helloworld.TestRandomNumberGenerator" />
        </classes>
    </test>
</suite>