TestNG Asserts example and explanation

Assertions in TestNG

Asserts helps us to verify the conditions of the test and decide whether test has failed or passed. A test is considered successful ONLY if it is completed without throwing any exception.

There will be many situations in the test where you just like to check the presence of an element. All you need to do is to put an assert statement on to it to verify its existence.

Here we are verifying if the page title is equal to 'Google' or not. If the page title is not matching with the text / title that we provided, it will fail the test case.

Different Asserts Statements
1) Assert.assertTrue() & Assert.assertFalse()

To explain you what is assertion, lets us look into below code sample.
I am going to create new TestNG class 'AssertTest'.

package automationFramework;

import java.util.concurrent.TimeUnit;
import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.safari.SafariDriver;
import org.testng.Assert;
import org.testng.annotations.Test;

public class AssertTest {
    public static WebDriver sDriver = new SafariDriver();
   
  @Test
  public void testOne() throws InterruptedException {
      sDriver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS);
      //Open website
      sDriver.get("http://amazon.com");
      //Verify Page title
      WebElement myAccountLink = sDriver.findElement(By.id("nav-link-yourAccount"));
     
      //Adding assertion check here. Test will only continue if below statement is True.
      Assert.assertTrue(myAccountLink.isDisplayed());
    //My Account Link will be clicked only if the above condition is true
      myAccountLink.click();
     
      Thread.sleep(1000);
  }
}

Let's run the code and verify the output.

 Assert.assertFalse() works opposite of Assert.assertTrue(). It means that if you want your test to continue only if when some certain element is not present on the page. You will use Assert false, so it will fail the test in case of the element present on the page.

Like wise there are many Assertions provided by the TestNG. The below are the few which are used commonly.
assertEqual(String actual,String expected) :- It takes two string arguments and checks whether both are equal, if not it will fail the test.

assertEqual(String actual,String expected, String message) :- It takes three string arguments and checks whether both are equal, if not it will fail the test and throws the message which we provide.
assertEquals(boolean actual,boolean expected) :- It takes two boolean arguments and checks whether both are equal, if not it will fail the test.

assertEquals(java.util.Collection actual, java.util.Collection expected, java.lang.String message) :- Takes two collection objects and verifies both collections contain the same elements and with the same order. if not it will fail the test with the given message.

Assert.assertTrue(condition) :- It takes one boolean arguments and checks that a condition is true, If it isn't, an AssertionError is thrown.

Assert.assertTrue(condition, message) :- It takes one boolean argument and String message. It Asserts that a condition is true. If it isn't, an AssertionError, with the given message, is thrown.

Assert.assertFalse(condition) :- It takes one boolean arguments and checks that a condition is false, If it isn't, an AssertionError is thrown.

Assert.assertFalse(condition, message) :- It takes one boolean argument and String message. It Asserts that a condition is false. If it isn't, an AssertionError, with the given message, is thrown.