Impossible d'Instancier une classe d'erreur - Selenium WebDriver

Je suis confronté à ce " Ne peut pas insantiate de la classe d'erreur sur l'exécution de l'une de mes cas de test dans selenium webdriver à l'aide de java.

Ci-dessous est la classe de la fonctionnalité de l'essai,

package Pages;
import java.util.List;
import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.support.ui.ExpectedConditions;
import org.openqa.selenium.support.ui.Select;
import org.openqa.selenium.support.ui.WebDriverWait;
import Lib.lib;
public class KnowledgeBase extends lib{
By sortBylink = By.xpath("html/body/div[1]/featured-studies-grid/div[2]/featured-studies-toolbar/div/div[2]/div[2]/div/div");
By featuredOption = By.xpath("html/body/div[1]/featured-studies-grid/div[2]/featured-studies-toolbar/div/div[2]/div[2]/div/ul/li[1]");
By mostRcnt = By.xpath("html/body/div[1]/featured-studies-grid/div[2]/featured-studies-toolbar/div/div[2]/div[2]/div/ul/li[2]");
String featOption = driver.findElement(By.xpath("html/body/div[1]/featured-studies-grid/div[2]/featured-studies-toolbar/div/div[2]/div[2]/div/ul/li[1]")).getText();
String mostRecent = driver.findElement(By.xpath("html/body/div[1]/featured-studies-grid/div[2]/featured-studies-toolbar/div/div[2]/div[2]/div/ul/li[2]")).getText();
public void initSBy() throws Exception
{
driver.findElement(sortBylink).click();
Thread.sleep(1500);
}
public void selectfO() throws Exception
{
driver.findElement(featuredOption).click();
Thread.sleep(5000);
}
public void selectMr() throws Exception
{
driver.findElement(mostRcnt).click();
Thread.sleep(5000);
}
public void sortBy(String sProp) throws Exception
{
this.initSBy();
if (sProp == featOption) {
this.selectfO();
}
else if (sProp == mostRecent){
this.selectMr();
}
else {
System.out.println("Incorrect option. Test failed.");
}
}
}

Ci-dessous est ma Classe de Cas de Test

package TestCases;
import org.testng.annotations.Test;
import Lib.lib;
import Pages.KnowledgeBase;
import Pages.LoginPage;
public class sortingTextKB extends lib {
LoginPage uLogin = new LoginPage();
KnowledgeBase sortObj = new KnowledgeBase();
//Logging In
@Test (priority = 1)
public void loggingIn() throws Exception
{
uLogin.loginToKB("[email protected]", "uziiiii");
}
//Sorting
@Test (priority = 2)
public void sortIn() throws Exception
{
sortObj.sortBy("Most Recent");
}
}

Ci-dessous est ma Lib de classe, qui contient le chrome de configuration du pilote d'

package Lib;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;
import org.openqa.selenium.chrome.ChromeOptions;
import org.testng.annotations.BeforeTest;
import org.testng.annotations.AfterTest;
public class lib {
protected static WebDriver driver = null;
@BeforeTest
public void chrome_extension()
{
System.setProperty("webdriver.chrome.driver", "chromedriver.exe");
ChromeOptions options = new ChromeOptions();
options.addArguments("--start-maximized");
driver = new ChromeDriver(options);
driver.get("http://www.testsite.com");
}
@AfterTest
public void quit()
{
driver.quit();
}
}

Quand je lance ma classe de cas de test, j'obtiens l'erreur suivante,

org.testng.TestNGException: 
Cannot instantiate class TestCases.sortingTextKB
at org.testng.internal.ObjectFactoryImpl.newInstance(ObjectFactoryImpl.java:38)
at org.testng.internal.ClassHelper.createInstance1(ClassHelper.java:387)
at org.testng.internal.ClassHelper.createInstance(ClassHelper.java:299)
at org.testng.internal.ClassImpl.getDefaultInstance(ClassImpl.java:110)
at org.testng.internal.ClassImpl.getInstances(ClassImpl.java:186)
at org.testng.internal.TestNGClassFinder.<init>(TestNGClassFinder.java:120)
at org.testng.TestRunner.initMethods(TestRunner.java:409)
at org.testng.TestRunner.init(TestRunner.java:235)
at org.testng.TestRunner.init(TestRunner.java:205)
at org.testng.TestRunner.<init>(TestRunner.java:160)
at org.testng.remote.RemoteTestNG$1.newTestRunner(RemoteTestNG.java:141)
at org.testng.remote.RemoteTestNG$DelegatingTestRunnerFactory.newTestRunner(RemoteTestNG.java:271)
at org.testng.SuiteRunner$ProxyTestRunnerFactory.newTestRunner(SuiteRunner.java:561)
at org.testng.SuiteRunner.init(SuiteRunner.java:157)
at org.testng.SuiteRunner.<init>(SuiteRunner.java:111)
at org.testng.TestNG.createSuiteRunner(TestNG.java:1299)
at org.testng.TestNG.createSuiteRunners(TestNG.java:1286)
at org.testng.TestNG.runSuitesLocally(TestNG.java:1140)
at org.testng.TestNG.run(TestNG.java:1057)
at org.testng.remote.RemoteTestNG.run(RemoteTestNG.java:111)
at org.testng.remote.RemoteTestNG.initAndRun(RemoteTestNG.java:204)
at org.testng.remote.RemoteTestNG.main(RemoteTestNG.java:175)
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at org.testng.internal.ObjectFactoryImpl.newInstance(ObjectFactoryImpl.java:29)
... 21 more
Caused by: java.lang.NullPointerException
at Pages.KnowledgeBase.<init>(KnowledgeBase.java:22)
at TestCases.sortingTextKB.<init>(sortingTextKB.java:12)
... 26 more

Suivant est le 22 ligne de la base de connaissances de la classe,

String featOption = driver.findElement(By.xpath("html/body/div[1]/featured-studies-grid/div[2]/featured-studies-toolbar/div/div[2]/div[2]/div/ul/li[1]")).getText();

S'il vous plaît laissez-moi savoir pourquoi, je suis confronté à cette "impossible d'instancier une classe d'erreur". Grâce