Another interesting feature available in TestNG is parametric testing. In most cases, you”ll come across a scenario where the business logic requires a hugely varying number of tests. Parameterized tests allow developers to run the same test over and over again using different values.

TestNG lets you pass parameters directly to your test methods in two different ways −

• With testng.xml
• With Data Providers

Passing Parameters with testng.xml

With this technique, you define the simple parameters in the testng.xml file and then reference those parameters in the source files. Let us have an example to demonstrate how to use this technique to pass parameters.

Create Test Case Class

• Create a java test class, say, ParameterizedTest1.java.

• Add test method parameterTest() to your test class. This method takes a string as input parameter.

• Add the annotation @Parameters(“myName”) to this method. The parameter would be passed a value from testng.xml, which we will see in the next step.

Create a java class file named ParameterizedTest1.java in /work/testng/src.

import org.testng.annotations.Parameters;
import org.testng.annotations.Test;

public class ParameterizedTest1 {
   @Test
   @Parameters("myName")
   public void parameterTest(String myName) {
      System.out.println("Parameterized value is : " + myName);
   }
}

Create testng.xml

Create testng.xml in /work/testng/src to execute test case(s).

<?xml version = "1.0" encoding = "UTF-8"?>
<!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd" >

<suite name = "Suite1">
   <test name = "test1">

      <parameter name = "myName" value="manisha"/>

      <classes>
         <class name = "ParameterizedTest1" />
      </classes>

   </test>
</suite>

We can also define the parameters at the <suite> level. Suppose we have defined myName at both <suite> and <test> levels. In such cases, regular scoping rules apply. It means that any class inside <test> tag will see the value of parameter defined in <test>, while the classes in the rest of the testng.xml file will see the value defined in <suite>.

Compile the test case class using javac.

/work/testng/src$ javac ParameterizedTest1.java

Now, run testng.xml, which will run the parameterTest method. TestNG will try to find a parameter named myName first in the <test> tag, and then, if it can’t find it, it searches in the <suit> tag that encloses it.

/work/testng/src$ java org.testng.TestNG testng.xml

Verify the output.

Parameterized value is : manisha

===============================================
Suite1
Total tests run: 1, Failures: 0, Skips: 0
===============================================

TestNG will automatically try to convert the value specified in testng.xml to the type of your parameter. Here are the types supported −

• String
• int/Integer
• boolean/Boolean
• byte/Byte
• char/Character
• double/Double
• float/Float
• long/Long
• short/Short

Passing Parameters with Dataproviders

When you need to pass complex parameters or parameters that need to be created from Java (complex objects, objects read from a property file or a database, etc.), parameters can be passed using Dataproviders.

A Data Provider is a method annotated with @DataProvider. This annotation has only one string attribute: its name. If the name is not supplied, the data provider’s name automatically defaults to the method’s name. A data provider returns an array of objects.

The following examples demonstrate how to use data providers. The first example is about @DataProvider using Vector, String, or Integer as parameter, and the second example is about @DataProvider using object as parameter.

Example 1

Here, the @DataProvider passes Integer and Boolean as parameter.

Create Java class

Create a java class called PrimeNumberChecker.java. This class checks if the number is prime. Create this class in /work/testng/src.

public class PrimeNumberChecker {
   public Boolean validate(final Integer primeNumber) {

      for (int i = 2; i < (primeNumber / 2); i++) {
         if (primeNumber % i == 0) {
            return false;
         }
      }
      return true;
   }
}

Create Test Case Class

• Create a java test class, say, ParamTestWithDataProvider1.java in /work/testng/src.

• Define the method primeNumbers(), which is defined as a Data provider using the annotation. This method returns an array of objects.

• Add the test method testPrimeNumberChecker() to your test class. This method takes an Integer and Boolean as input parameters. This method validates if the parameter passed is a prime number.

• Add the annotation @Test(dataProvider = “test1”) to this method. The attribute dataProvider is mapped to “test1”.

Following are the contents of ParamTestWithDataProvider1.java.

import org.testng.Assert;
import org.testng.annotations.BeforeMethod;
import org.testng.annotations.DataProvider;
import org.testng.annotations.Test;

public class ParamTestWithDataProvider1 {
   private PrimeNumberChecker primeNumberChecker;

   @BeforeMethod
   public void initialize() {
      primeNumberChecker = new PrimeNumberChecker();
   }

   @DataProvider(name = "test1")
   public static Object[][] primeNumbers() {
      return new Object[][] {{2, true}, {6, false}, {19, true}, {22, false}, {23, true}};
   }

   // This test will run 4 times since we have 5 parameters defined
   @Test(dataProvider = "test1")
   public void testPrimeNumberChecker(Integer inputNumber, Boolean expectedResult) {
      System.out.println(inputNumber + " " + expectedResult);
      Assert.assertEquals(expectedResult, primeNumberChecker.validate(inputNumber));
   }
}

Create testng.xml

Create a testng.xml /work/testng/src to execute Test case(s).

<?xml version = "1.0" encoding = "UTF-8"?>
<!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd" >

<suite name = "Suite1">
   <test name = "test1">
      <classes>
         <class name = "ParamTestWithDataProvider1" />
      </classes>
   </test>
</suite>

Compile the Test case class using javac.

/work/testng/src$ javac ParamTestWithDataProvider1.java PrimeNumberChecker.java

Now, run testng.xml.

/work/testng/src$ java org.testng.TestNG testng.xml

Verify the output.

   2 true
   6 false
   19 true
   22 false
   23 true

===============================================
   Suite1
   Total tests run: 5, Failures: 0, Skips: 0
===============================================

Example 2

Here, the @DataProvider passes Object as parameter.

Create Java class

Create a java class Bean.java, which is a simple object with get/set methods, in /work/testng/src.

public class Bean {
   private String val;
   private int i;

   public Bean(String val, int i) {
      this.val = val;
      this.i = i;
   }

   public String getVal() {
      return val;
   }

   public void setVal(String val) {
      this.val = val;
   }

   public int getI() {
      return i;
   }

   public void setI(int i) {
      this.i = i;
   }
}

Create Test Case Class

• Create a java test class, say, ParamTestWithDataProvider2.java.

• Define the method primeNumbers(), which is defined as a data provider using annotation. This method returns an array of object.

• Add the test method testMethod() to your test class. This method takes an object bean as parameter.

• Add the annotation @Test(dataProvider = “test1”) to this method. The attribute dataProvider is mapped to “test1”.

Create a java class file named ParamTestWithDataProvider2.java in /work/testng/src.

import org.testng.annotations.DataProvider;
import org.testng.annotations.Test;

public class ParamTestWithDataProvider2 {
   @DataProvider(name = "test1")
   public static Object[][] primeNumbers() {
      return new Object[][] { { new Bean("hi I am the bean", 111) } };
   }

   @Test(dataProvider = "test1")
   public void testMethod(Bean myBean) {
      System.out.println(myBean.getVal() + " " + myBean.getI());
   }
}

Create testng.xml

Create testng.xml in /work/testng/src to execute test case(s).

<?xml version = "1.0" encoding = "UTF-8"?>
<!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd" >

<suite name = "Suite1">
   <test name = "test1">
      <classes>
         <class name = "ParamTestWithDataProvider2" />
      </classes>
   </test>
</suite>

Compile the test case class using javac.

/work/testng/src$ javac ParamTestWithDataProvider2.java Bean.java

Now, run testng.xml.

/work/testng/src$ java org.testng.TestNG testng.xml

Verify the output.

   hi I am the bean 111

===============================================
   Suite1
   Total tests run: 1, Failures: 0, Skips: 0
===============================================