java.lang.Exception：测试类应该只有一个公共构造函数

Posted 2023-02-26

【中文标题】java.lang.Exception：测试类应该只有一个公共构造函数

【英文标题】：java.lang.Exception: Test class should have exactly one public constructor

【发布时间】：2017-03-29 01:26:20

【问题描述】：

我正在关注junit测试

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();    

这是在扔

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.

【参考方案1】：

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

应该是

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

【讨论】：

正是这个，就像错误说的那样：测试类应该只有一个公共构造函数所以必须有一个公共构造函数....有时可以回答提问的人使用“请阅读控制台的输出”。因为在我看来这不是一个好问题（答案已经由输出给出），所以我对这个问题投了反对票，对答案投了赞成票。

【参考方案2】：

在编写JUnit时要记住的是，在执行时它会在执行测试方法之前调用测试类的构造函数。您可以通过将 System.out.println 消息放入构造函数本身来验证它

在您的代码中，您已将构造函数定义为私有，因此测试框架将无法实例化您的测试类以执行测试方法，将范围更改为公共。

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

【参考方案3】：

我在尝试在 Eclipse 中运行单元测试时遇到此错误，结果发现问题出在 Eclipse。使用 gradle 从命令行运行它会返回一个不同的错误 - another 单元测试无效。修复其他无效测试修复了此错误。非常感谢，Eclipse！