lazyloading of data providers in testng

Question

I am trying to achieve lazy loading of data provider for my tests but it is not working . Below is my code snippet for factory annotated method:

import java.util.Iterator;

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

public class TF
{
    @DataProvider(name="TestInstances")
    public static Iterator<Object> testInstancesDP()
    {
        return new Iterator<Object>()
        {
            int counter=1;
            int MAX;
            {
                MAX=4;
            }

            @Override
            public boolean hasNext()
            {
                return counter<=MAX;
            }

            @Override
            public Object next()
            {
                System.out.println("passing "+counter+" iterator instance");
                return new Object[] {counter++};
            }

            @Override
            public void remove()
            {
                //TODO: IllegalOperationException
            }
        };
    }

    private int order;

    @Factory(dataProvider="TestInstances",dataProviderClass=TF.class)
    public TF(int order)
    {
        this.order=order;
        System.out.println("TF Instance created : "+order);
    }

    @DataProvider
    public Iterator<Object> testDataProvider()
    {
        return new Iterator<Object>()
        {
            int counter=1;
            int MAX;
            {
                MAX=TF.this.order;
            }

            @Override
            public boolean hasNext()
            {
                return counter<=MAX;
            }

            @Override
            public Object next()
            {
                System.out.println("passing "+counter+" as DP");
                return new Object[] {"DP"+counter++};
            }

            @Override
            public void remove()
            {
                //TODO: IllegalOperationException
            }

        };
    }

    @Test(dataProvider="testDataProvider")
    public void testStepExecutor(String str)
    {
        System.out.println("Test method execution : "+str);
    }

    @AfterClass
    public void tearDown()
    {
        System.out.println("Tear Down: "+this.order);
    }

    /**
     * @return the order
     */
    public int getOrder()
    {
        return order;
    }
}

• Actual Output:

  passing 1 iterator instance TF Instance created : 1 passing 2 iterator instance TF Instance created : 2 passing 3 iterator instance TF Instance created : 3 passing 4 iterator instance TF Instance created : 4 [TestNG] Running: Command line suite

  passing 1 as DP Test method execution : DP1 Tear Down: 1 passing 1 as DP Test method execution : DP1 passing 2 as DP Test method execution : DP2 Tear Down: 2 passing 1 as DP Test method execution : DP1 passing 2 as DP Test method execution : DP2 passing 3 as DP Test method execution : DP3 Tear Down: 3 passing 1 as DP Test method execution : DP1 passing 2 as DP Test method execution : DP2 passing 3 as DP Test method execution : DP3 passing 4 as DP Test method execution : DP4 Tear Down: 4

  =============================================== Command line suite

  Total tests run: 10, Failures: 0, Skips: 0

• Expected output

  passing 1 iterator instance TF Instance created : 1 passing 1 as DP Test method execution : DP1 Tear Down: 1 passing 2 iterator instance TF Instance created : 2 passing 1 as DP Test method execution : DP1 passing 2 as DP Test method execution : DP2 Tear Down: 2 passing 3 iterator instance TF Instance created : 3 passing 1 as DP Test method execution : DP1 passing 2 as DP Test method execution : DP2 passing 3 as DP Test method execution : DP3 Tear Down: 3 passing 4 iterator instance TF Instance created : 4 passing 1 as DP Test method execution : DP1 passing 2 as DP Test method execution : DP2 passing 3 as DP Test method execution : DP3 passing 4 as DP Test method execution : DP4 Tear Down: 4 [TestNG] Running: Command line suite

  =============================================== Command line suite

  Total tests run: 10, Failures: 0, Skips: 0

Is this a bug in TestNG implementation or lazyloading is not supported for Factory.. TIA

Answer 1

Lazyloading of data provirder is not working for Factory because TestNG is currently invoking all factory methods before running tests.