TestNG Assertions

TestNG Assertions:

While using Selenium for automated testing of web applications, we need to add validations in our tests to report them as pass or fail. And assertions can let us do that within a single line of code. Here, you’ll learn how to use TestNG assertions and know the different methods to assert conditions.

Assertions give you a way, other than If-Else blocks, to test conditions. They are not only easy to use but also eliminate the chances of making any error in forming test conditions. Hence, it’s always beneficial to use them in Selenium WebDriver projects.

There are two types of assertions in Selenium that we can place in our test scripts using TestNG:

  1. Hard Assertion.
  2. Soft Assertion.

1- Hard Assertion:

It is the default assert mechanism built into TestNG’s <org.testng.assert> package. We use it when a test has to stop immediately after the assertion fails.

Please refer below two scenarios to understand the concept.

Hard Assertion – Scenario(1)

Follow the below code which includes one assert call, which get passed and so the test case.

package Assertion;
import org.testng.Assert;
import org.testng.annotations.Test;

public class HardAssertion {
	String empName = "Google";@Test
	public void HardAssertion_TC001() {
		Assert.assertEquals(empName, "Google");
		System.out.println("Successfully passed!");
	}
}

Output:

Successfully passed!
[Utils] Attempting to create D:\WorkSpace\DemoTestNG\test-output\Default suite\Default test.xml
[Utils]   Directory D:\WorkSpace\DemoTestNG\test-output\Default suite exists: true
PASSED: HardAssertion_TC001

You can see the message “Successfully passed!” getting appeared in the execution output.

Hard Assertion – Scenario(2)

Follow the below code which includes one assert call, which got failed and so it leads to the end of the test case.

package Assertion;
import org.testng.Assert;
import org.testng.annotations.Test;

public class HardAssertion {
	String empName = "abc";@Test
	public void HardAssertion_TC001() {
		Assert.assertEquals(empName, "xyz");
		System.out.println("Successfully passed!");
	}
}

Output:

FAILED: HardAssertion_TC001
java.lang.AssertionError: expected [abc] but found [xyz]

After the expected string didn’t match the actual string, the execution of test case stopped immediately.

2- Soft Assertion:

It is a custom assert mechanism supported by TestNG’s <org.testng.asserts.Softassert> package. We use it when a test has to continue execution even after an assertion fails in the sequence.

Follow the below code which creates a Soft assertion object. Then, it includes multiple assert methods followed by a <assertAll()> call. The first assert fails but that doesn’t interrupt the execution. It is because of the <assertAll()> method which lets the other assert calls to complete.

package Assertion;
import org.testng.annotations.Test;
import org.testng.asserts.SoftAssert;

public class SoftAssertion {

	SoftAssert softAssert = new SoftAssert();
	String empName = "Page";
	String companyName = "Google";@Test
	public void SoftAssertion_TC001() {
		softAssert.assertEquals(companyName, "GoogleSearch");
		softAssert.assertEquals(empName, "Page");
		System.out.println("Last statement gets executed!");
		softAssert.assertAll();
	}
}

Output:

...
Last statement gets executed!
[Utils] Attempting to create D:\WorkSpace\DemoTestNG\test-output\Default suite\Default test.xml
[Utils]   Directory D:\WorkSpace\DemoTestNG\test-output\Default suite exists: true
FAILED: SoftAssertion_TC001
java.lang.AssertionError: The following asserts failed:
  expected [Google] but found [GoogleSearch]

You can cross-check from the output above, that the message <The Last statement gets executed!> appeared there even after one of the assert calls failed.

The Assert Methods Available In TestNG.

Let’s now quickly outline the methods that you can call from Selenium code for using TestNG assertions.

 
Methods Description
1- assertEquals(
String actual,
String expected);
1- It accepts two string arguments.
2- It’ll check whether both are equal, if not it’ll fail the test.
2- assertEquals(
String actual,
String expected,
String message);
1- It accepts three string arguments.
2- It’ll test whether both are same, if not it’ll fail the test.
3- Also, it’ll throw a message that we provide.
3- assertEquals(
boolean actual,
boolean expected);
1- It assumes two boolean arguments.
2- It tests them for equality, if not it’ll fail the test.
4- assertEquals(
java.util.Collection actual,
java.util.Collection expected,
java.lang.String message);
1- It accepts two collection type objects.
2- It checks whether they hold same elements and with the same order.
3- It’ll fail the test if the above condition doesn’t meet.
4- Also, you’ll see the message appear in the report.
5- assertTrue(
<condition>);
1- It accepts one boolean argument.
2- It tests that the given condition is true.
3- If it fails, then an <AssertionError> would occur.
6- assertTrue(
<condition>,
message);
1- It assumes one boolean argument and a message.
2- It asserts that the given condition is true.
3- If it fails, then an <AssertionError> would occur with the message you passed.
7- assertFalse(
<condition>);
1- It accepts one boolean argument.
2- It checks that the given condition is false.
3- If it doesn’t pass, then an <AssertionError> would occur.
8- assertFalse(
<condition>,
message);
1- It assumes one boolean argument and a message.
2- It asserts that the given condition is false.
3- If it fails, then an <AssertionError> would occur with the message you passed.

 

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