TestNG: ITestContext

ITestContext is basically used to store and share data across the tests in selenium by using TestNG framework.

Let us consider below scenario –We have 10 test cases (@Test methods) to be executed to complete one end to end test case.
Now in call 10 test cases (@Test methods) we are sharing some data like “Customer_id”, which should be unique and same in our end to end test case i.e. in our 10 @Test methods. During the execution of end to end test case, it should be same.

To handle this scenario, we have two ways –   

1.    If all 10 @Test methods are in same class, then we can store “Customer_id”  in a class level variable (instance variable)  and share it. But it may require high maintenance.
2. Another way to handle this is, ITestContextLet us see How ITestContext works.In any @Test method, we can use “iTestContext” by passing it as a parameter to the method

@Test
 public void test1a(ITestContext context){
 
 }

Here, we can set the value that we want to share  in ITestContex, as below 

@Test
 public void test1a(ITestContext context){
 
  String Customer_id = "C11012034";
  context.setAttribute("CustID", Customer_id);
 } 

Now, we can get this value, which is stored in ITestContext variable with other tests, as below –

String Customer_id1 = (String) context.getAttribute("CustID");

Below piece of code can help you to understand how ITestContext works.

package iTestContextLearn;

import org.testng.ITestContext;
import org.testng.annotations.BeforeTest;
import org.testng.annotations.Test;

public class Test1 {

 @BeforeTest
 public void SetData(ITestContext context){
 
  String Customer_id = "C11012034";
  context.setAttribute("CustID", Customer_id);
  System.out.println("Value is stored in ITestContext");
  System.out.println("+++++++++++++++++++++++++++++++++++++++++++++++++");

 }
 @Test
 public void Test1a(ITestContext context){
  String Customer_id1 = (String) context.getAttribute("CustID");
  System.out.println("In Test1, Value stored in context is: "+Customer_id1);
  System.out.println("+++++++++++++++++++++++++++++++++++++++++++++++++");

 }
 @Test
 public void Test2a(ITestContext context){
  String Customer_id1 = (String) context.getAttribute("CustID");
  System.out.println("In Test2, Value stored in context is: "+Customer_id1);
  System.out.println("+++++++++++++++++++++++++++++++++++++++++++++++++");

 }
}

Note: We can pass this context to methods present in different classes and can use.

Source:
https://automationtalks.com/2017/07/06/what-is-itestcontext-in-testng-seleniu/