NullPointerException in WebDriverBackedSelenium - selenium-webdriver

Question

I'm new to selenium and still exploring it. I'm trying to test an ajax element on a site. On clicking the element some text pops on some area on the page. I've run this test on RC as well as WebDriver. It's working fine. Now I want(just out of curiosity) to test it via WebDriverBackedSelenium. But it's throwing an error. The code is:
import com.thoughtworks.selenium.SeleneseTestBase;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebDriverBackedSelenium;
import org.openqa.selenium.internal.WrapsDriver;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
public class CheckElements extends SeleneseTestBase {
#Before
public void setUp() throws Exception {
String baseUrl = "path/to/the/site";
WebDriver driver = ((WrapsDriver) selenium).getWrappedDriver();
selenium = new WebDriverBackedSelenium(driver, baseUrl);
}
The error is:
java.lang.NullPointerException
at com.CheckElements.setUp(CheckElements.java:17)
I believe the main problem is in setup method. I'm using selenium standalone server 2.0 and junit 4.7. Can you please tell where am I going wrong?
Another Question??
If I write the same test as below, the test runs fine but it doesn't give error even if the text doesn't matches what is required.
import com.thoughtworks.selenium.SeleneseTestBase;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebDriverBackedSelenium;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
public class New extends SeleneseTestBase {
WebDriver driver;
#Before
public void setUp() throws Exception {
driver = new FirefoxDriver();
String baseUrl = "path/to/the/link";
selenium = new WebDriverBackedSelenium(driver, baseUrl);
}
I hope I'm clear in my questions. Thanks.

Answer 1

I would highly expect this to be the issue:
WebDriver driver = ((WrapsDriver) selenium).getWrappedDriver();
The driver instance is probably null.
The difference being in your other test, you are explicitly creating it into a FirefoxDriver:
driver = new FirefoxDriver();