TestNG +Selenium : How to resolve exception: "java.lang.IllegalStateException"?

Question

I am getting following error when run my selenium webdriver program using testNG (Using Eclipse Kepler service release 2)

Cannot instantiate class TestNG.TestNGClass
    at org.testng.internal.ObjectFactoryImpl.newInstance(ObjectFactoryImpl.java:40)
    at org.testng.internal.ClassHelper.createInstance1(ClassHelper.java:373)
    at org.testng.internal.ClassHelper.createInstance(ClassHelper.java:285)
    at org.testng.internal.ClassImpl.getDefaultInstance(ClassImpl.java:126)
    at org.testng.internal.ClassImpl.getInstances(ClassImpl.java:191)
    at org.testng.TestClass.getInstances(TestClass.java:104)
    at org.testng.TestClass.initTestClassesAndInstances(TestClass.java:90)
    at org.testng.TestClass.init(TestClass.java:82)
    at org.testng.TestClass.<init>(TestClass.java:45)
    at org.testng.TestRunner.initMethods(TestRunner.java:422)
    at org.testng.TestRunner.init(TestRunner.java:252)
    at org.testng.TestRunner.init(TestRunner.java:222)
    at org.testng.TestRunner.<init>(TestRunner.java:171)
    at org.testng.remote.support.RemoteTestNG6_9_10$1.newTestRunner(RemoteTestNG6_9_10.java:28)
    at org.testng.remote.support.RemoteTestNG6_9_10$DelegatingTestRunnerFactory.newTestRunner(RemoteTestNG6_9_10.java:61)
    at org.testng.SuiteRunner$ProxyTestRunnerFactory.newTestRunner(SuiteRunner.java:604)
    at org.testng.SuiteRunner.init(SuiteRunner.java:170)
    at org.testng.SuiteRunner.<init>(SuiteRunner.java:117)
    at org.testng.TestNG.createSuiteRunner(TestNG.java:1359)
    at org.testng.TestNG.createSuiteRunners(TestNG.java:1346)
    at org.testng.TestNG.runSuitesLocally(TestNG.java:1200)
    at org.testng.TestNG.runSuites(TestNG.java:1124)
    at org.testng.TestNG.run(TestNG.java:1096)
    at org.testng.remote.AbstractRemoteTestNG.run(AbstractRemoteTestNG.java:132)
    at org.testng.remote.RemoteTestNG.initAndRun(RemoteTestNG.java:236)
    at org.testng.remote.RemoteTestNG.main(RemoteTestNG.java:81)
Caused by: java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
    at org.testng.internal.ObjectFactoryImpl.newInstance(ObjectFactoryImpl.java:29)
    ... 25 more
Caused by: java.lang.IllegalStateException: The path to the driver executable must be set by the webdriver.gecko.driver system property; for more information, see https://github.com/mozilla/geckodriver. The latest version can be downloaded from https://github.com/mozilla/geckodriver/releases
    at com.google.common.base.Preconditions.checkState(Preconditions.java:199)
    at org.openqa.selenium.remote.service.DriverService.findExecutable(DriverService.java:109)
    at org.openqa.selenium.firefox.GeckoDriverService.access$000(GeckoDriverService.java:37)
    at org.openqa.selenium.firefox.GeckoDriverService$Builder.findDefaultExecutable(GeckoDriverService.java:95)
    at org.openqa.selenium.remote.service.DriverService$Builder.build(DriverService.java:296)
    at org.openqa.selenium.firefox.FirefoxDriver.createCommandExecutor(FirefoxDriver.java:277)
    at org.openqa.selenium.firefox.FirefoxDriver.<init>(FirefoxDriver.java:247)
    at org.openqa.selenium.firefox.FirefoxDriver.<init>(FirefoxDriver.java:242)
    at org.openqa.selenium.firefox.FirefoxDriver.<init>(FirefoxDriver.java:238)
    at org.openqa.selenium.firefox.FirefoxDriver.<init>(FirefoxDriver.java:127)
    at TestNG.TestNGClass.<init>(TestNGClass.java:15)
    ... 30 more

Here is the Java program

package TestNG;

import java.util.concurrent.TimeUnit;

import org.openqa.selenium.*;
import org.openqa.selenium.firefox.FirefoxDriver;

import org.testng.annotations.AfterTest;
import org.testng.annotations.BeforeTest;
import org.testng.annotations.Test;

public class TestNGClass
{

    WebDriver driver = new FirefoxDriver();

   @BeforeTest
   public void launchapp()
   {
       System.out.println("Before test");
       // Puts an Implicit wait, Will wait for 10 seconds before throwing exception

      driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS);
      // Launch website
      driver.navigate().to("http://www.calculator.net");
      driver.manage().window().maximize();
   }
   @Test
   public void calculatepercent()
   {
       System.out.println("Starting calculator percent");
       // Click on Math Calculators
      driver.findElement(By.xpath(".//*[@id='menu']/div[3]/a")).click();

      // Click on Percent Calculators
      driver.findElement(By.xpath(".//*[@id='menu']/div[4]/div[3]/a")).click();

      // Enter value 10 in the first number of the percent Calculator
      driver.findElement(By.id("cpar1")).sendKeys("10");

      // Enter value 50 in the second number of the percent Calculator
      driver.findElement(By.id("cpar2")).sendKeys("50");

      // Click Calculate Button
      driver.findElement(By.xpath(".//*[@id='content']/table/tbody/tr/td[2]/input")).click();

      // Get the Result Text based on its xpath
      String result = driver.findElement(By.xpath(".//*[@id='content']/p[2]/span/font/b")).getText();

      // Print a Log In message to the screen
      System.out.println(" The Result is " + result);

      if(result.equals("5"))
      {
         System.out.println(" The Result is Pass");
      }
      else
      {
         System.out.println(" The Result is Fail");
      }
   }
   @AfterTest
   public void terminatetest()
   {
      driver.close();
   }
}

And here is the XML file

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd">
<suite name="Suite">
  <test name="Test">
    <classes>
      <class name="TestNG.TestNGClass"/>
    </classes>
  </test> <!-- Test -->
</suite> <!-- Suite -->

Answer 1

It can't find the driver for Firefox. Downloading the GeckoDriver and putting it into your Bin folder or setting a System Property for webdriver.gecko.driver should fix the problem.

Answer 2

Exception: "java.lang.IllegalStateException"

• This exception is especially useful when your class has some state (state machine?) that changes over time, making some methods irrelevant

• This is generally the exception to throw if the invocation is illegal because of the state of the receiving object. For example, this would be the exception to throw if the caller attempted to use some object before it had been properly initialized.