Parameterization in TestNG Using @DataProvider

Parameterization in TestNG allows you to run a test multiple times with different inputs, which is essential for testing a wide variety of data-driven scenarios. The most common way to achieve parameterization in TestNG is through the use of the @DataProvider annotation. It allows you to feed multiple sets of data to a test method, which is useful for running the same test with various data sets without duplicating code.

Here’s a breakdown of how parameterization using @DataProvider works in TestNG and how to implement it:

1. What is @DataProvider?

The @DataProvider annotation in TestNG allows you to create a method that supplies multiple sets of data to a test method. This helps in executing the same test with different inputs, which is useful for running parameterized tests.

The @DataProvider method returns a 2D Object array (or List<Object[]>) containing different sets of data.

The data in the array is passed to the test method as parameters.

2. Key Components of @DataProvider

DataProvider Method: A method that returns a 2D array of objects, where each row represents a different set of test data.

Test Method: The method you want to run multiple times, accepting parameters that will be provided by the @DataProvider.

3. How to Use @DataProvider in TestNG

Step-by-Step Example

Let's say we want to run the same test method with multiple sets of data to validate a simple login functionality.

Example 1: Basic Usage of @DataProvider

Test Class (LoginTest.java):

import org.testng.annotations.Test;

import org.testng.annotations.DataProvider;

public class LoginTest {

// DataProvider method that supplies data

@DataProvider(name = "loginData")

public Object[][] loginData() {

return new Object[][] {

{ "user1", "password1" }, // Test data 1

{ "user2", "password2" }, // Test data 2

{ "user3", "password3" }, // Test data 3

};

}

// Test method using the data provided by DataProvider

@Test(dataProvider = "loginData")

public void testLogin(String username, String password) {

System.out.println("Testing login for user: " + username + " with password: " + password);

// Add your actual login validation logic here

}

Explanation:

@DataProvider Annotation:

@DataProvider(name = "loginData") provides the name for the data provider.

The loginData method returns a 2D array of Objects. Each row in the array represents a set of test data (in this case, a username and password).

Test Method:

The testLogin method accepts parameters (username and password) that will be supplied by the @DataProvider.

Output:

TestNG will run testLogin three times, each time with different values for username and password.

Sample Output:

Testing login for user: user1 with password: password1

Testing login for user: user2 with password: password2

Testing login for user: user3 with password: password3

4. Complex DataProvider Example

You can also pass complex objects such as custom classes, and data types other than simple strings.

Example 2: Using Custom Objects with @DataProvider

Test Class (RegistrationTest.java):

import org.testng.annotations.Test;

import org.testng.annotations.DataProvider;

class User {

String username;

String email;

public User(String username, String email) {

this.username = username;

this.email = email;

}

@Override

public String toString() {

return "User{username='" + username + "', email='" + email + "'}";

}

public class RegistrationTest {

// DataProvider method providing custom User objects

@DataProvider(name = "userData")

public Object[][] userData() {

return new Object[][] {

{ new User("user1", "user1@example.com") },

{ new User("user2", "user2@example.com") },

{ new User("user3", "user3@example.com") }

};

}

// Test method using the custom objects from DataProvider

@Test(dataProvider = "userData")

public void testRegistration(User user) {

System.out.println("Testing registration for: " + user);

// Add your actual registration validation logic here

}

Explanation:

In this example, we are passing a custom User object instead of just simple strings.

The User class has two fields (username and email) and a constructor to initialize these fields.

The @DataProvider method returns a 2D array of User objects, and the testRegistration method receives a User object for each iteration.

Sample Output:

Testing registration for: User{username='user1', email='user1@example.com'}

Testing registration for: User{username='user2', email='user2@example.com'}

Testing registration for: User{username='user3', email='user3@example.com'}

5. Parallel Execution with @DataProvider

If you need to run parameterized tests in parallel, TestNG can handle it with proper configuration.

Example 3: Running Tests in Parallel with @DataProvider

You can enable parallel execution in TestNG XML or programmatically by setting the parallel attribute in the TestNG configuration file.

In your TestNG XML file:

</classes>

</test>

</suite>

In this setup, TestNG will run the parameterized tests for LoginTest in parallel, depending on the thread-count specified.

6. Tips for Using @DataProvider

Data Consistency: Ensure that the data provided by @DataProvider aligns with the expected format of your test method parameters.

Dynamic Data: You can generate dynamic test data by using data sources like Excel, CSV, or databases, and have the @DataProvider method fetch data at runtime.

Use Multiple @DataProvider Methods: You can have multiple @DataProvider methods, each providing different sets of data to various test methods.

7. Conclusion

The @DataProvider annotation in TestNG is an extremely useful tool for parameterizing tests, enabling data-driven testing. By using @DataProvider, you can run the same test multiple times with different inputs, reducing code duplication and increasing test coverage.

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December 08, 2025