java.lang.Exception: Test class should have exactly one public constructor

Question

I've following junit test

package test.java.com.unit;
import com.saucelabs.common.SauceOnDemandAuthentication;
import com.saucelabs.common.SauceOnDemandSessionIdProvider;
import com.saucelabs.junit.Parallelized;
import com.saucelabs.junit.SauceOnDemandTestWatcher;
import org.junit.After;
import org.junit.Before;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.TestName;
import org.junit.runner.RunWith;
import org.junit.runners.Parameterized;
import org.openqa.selenium.Platform;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.remote.CapabilityType;
import org.openqa.selenium.remote.DesiredCapabilities;
import org.openqa.selenium.remote.RemoteWebDriver;

import java.net.URL;
import java.util.LinkedList;

import static org.junit.Assert.assertEquals;

@RunWith(Parallelized.class)
public class WebDriverTest implements SauceOnDemandSessionIdProvider {


public SauceOnDemandAuthentication authentication = new SauceOnDemandAuthentication("USER_NAME", "ACCESS_KEY");

private String browser;
private String os;
private String version;

public @Rule SauceOnDemandTestWatcher resultReportingTestWatcher = new SauceOnDemandTestWatcher(this, authentication);

public @Rule TestName testName = new TestName();

private WebDriverTest(String os, String version, String browser) {
 super();
 this.os= os;
 this.version= version;
 this.browser= browser;
}

@SuppressWarnings({ "unchecked", "rawtypes" })
@Parameterized.Parameters
public static LinkedList browsersStrings() throws Exception {
LinkedList browsers = new LinkedList();
 browsers.add(new String[]{Platform.XP.toString(), "26", "firefox"});
 browsers.add(new String[]{Platform.WIN8.toString(), "10", "internet explorer"});
  browsers.add(new String[]{Platform.MAC.toString(), "5", "safari"});
 browsers.add(new String[]{Platform.MAC.toString(), "7", "iphone"});
browsers.add(new String[]{Platform.LINUX.toString(), "30", "chrome"});
 browsers.add(new String[]{Platform.ANDROID.toString(), "4.0", "android"});
return browsers;
}
private WebDriver driver;
private String sessionId;

@Before
public void setUp() throws Exception {

DesiredCapabilities capabilities = new DesiredCapabilities();
capabilities.setCapability(CapabilityType.BROWSER_NAME, browser);
capabilities.setCapability(CapabilityType.VERSION, version);
capabilities.setCapability(CapabilityType.PLATFORM,  Platform.valueOf(os));

if(browser.equalsIgnoreCase("android"))
{
 capabilities.setCapability("device-type", "tablet");
  capabilities.setCapability("device-orientation", "portrait");
}
else if(browser.equalsIgnoreCase("iphone"))
{
  capabilities.setCapability("device-orientation", "portrait");
}

String name = testName.getMethodName() + ": "+ browser+ " "+ version+ " "+ Platform.valueOf(os);
capabilities.setCapability("name",name);
this.driver= new RemoteWebDriver(new URL("http://"+ authentication.getUsername() + ":"+ authentication.getAccessKey() + "@ondemand.saucelabs.com:80/wd/hub"),capabilities);
this.sessionId= ((RemoteWebDriver)driver).getSessionId().toString();

}

@Override
public String getSessionId() {
return sessionId;
}

@Test
public void webDriver() throws Exception {
// Simple test -just go to the site and verify the title.
 driver.get("https://www.google.com/");
 assertEquals("To Do List", driver.getTitle());
}

@After
public void tearDown() throws Exception {
 driver.quit(); }   }

which is throwing

java.lang.Exception: Test class should have exactly one public constructor
    at org.junit.runners.BlockJUnit4ClassRunner.validateOnlyOneConstructor(BlockJUnit4ClassRunner.java:158)
    at org.junit.runners.parameterized.BlockJUnit4ClassRunnerWithParameters.validateConstructor(BlockJUnit4ClassRunnerWithParameters.java:88)
    at org.junit.runners.BlockJUnit4ClassRunner.collectInitializationErrors(BlockJUnit4ClassRunner.java:127)
    at org.junit.runners.ParentRunner.validate(ParentRunner.java:416)
    at org.junit.runners.ParentRunner.<init>(ParentRunner.java:84)
    at org.junit.runners.BlockJUnit4ClassRunner.<init>(BlockJUnit4ClassRunner.java:65)
    at org.junit.runners.parameterized.BlockJUnit4ClassRunnerWithParameters.<init>(BlockJUnit4ClassRunnerWithParameters.java:27)
    at org.junit.runners.parameterized.BlockJUnit4ClassRunnerWithParametersFactory.createRunnerForTestWithParameters(BlockJUnit4ClassRunnerWithParametersFactory.java:16)
    at org.junit.runners.Parameterized.createRunnersForParameters(Parameterized.java:313)
    at org.junit.runners.Parameterized.<init>(Parameterized.java:248)
    at com.saucelabs.junit.Parallelized.<init>(Parallelized.java:88)
    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:422)
    at org.junit.internal.builders.AnnotatedBuilder.buildRunner(AnnotatedBuilder.java:104)
    at org.junit.internal.builders.AnnotatedBuilder.runnerForClass(AnnotatedBuilder.java:86)
    at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:59)
    at org.junit.internal.builders.AllDefaultPossibilitiesBuilder.runnerForClass(AllDefaultPossibilitiesBuilder.java:26)
    at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:59)
    at org.junit.internal.requests.ClassRequest.getRunner(ClassRequest.java:33)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.<init>(JUnit4TestReference.java:33)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestClassReference.<init>(JUnit4TestClassReference.java:25)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestLoader.createTest(JUnit4TestLoader.java:48)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestLoader.loadTests(JUnit4TestLoader.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:452)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

exception while running test. Can someone help finding the solution.

Solution

private WebDriverTest(String os, String version, String browser) {
 super();
 this.os= os;
 this.version= version;
 this.browser= browser;
}

should be

public WebDriverTest(String os, String version, String browser) {
 super();
 this.os= os;
 this.version= version;
 this.browser= browser;
}

Comments

[Jeroen van Dijk-Jun]

Exactly this, like the error said: Test class should have exactly one public constructor so there has to be a public constructor.... Sometimes peope asking questions can be answered with "pls read the output of your console". Because in my opinion this is no good question (the answer is already given by the output), I downvoted the question, and upvoted the answer.