为啥我在 Selenium 中收到 AssertionError？

Posted 2023-02-26

【中文标题】为啥我在 Selenium 中收到 AssertionError？

【英文标题】：Why am I getting AssertionError in Selenium?为什么我在 Selenium 中收到 AssertionError？

【发布时间】：2019-01-13 09:06:03

【问题描述】：

您能否建议，当测试运行正常，但在测试结束时在 Selenium 中出现错误和长堆栈跟踪时，我们能做些什么？

package com.example.tests;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.fail;

import java.util.NoSuchElementException;
import java.util.concurrent.TimeUnit;

import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import org.openqa.selenium.Alert;
import org.openqa.selenium.By;
import org.openqa.selenium.NoAlertPresentException;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;
import org.openqa.selenium.support.ui.ExpectedConditions;
import org.openqa.selenium.support.ui.WebDriverWait;

public class AddGroupTests 
  private WebDriver driver;
  private boolean acceptNextAlert = true;
  private StringBuffer verificationErrors = new StringBuffer();

  @Before
  public void setUp() throws Exception 
    System.setProperty("webdriver.chrome.driver","C:\\selenium-java-3.12.0\\chromedriver.exe");
    driver = new ChromeDriver();
    driver.manage().timeouts().implicitlyWait(30, TimeUnit.SECONDS);
  

  @Test
  public void testAddNewGroup() throws Exception 
    openMainPage();
    findFrame();
    logIn();
    goToGroupPage();
    fillFormAndSubmit("Group1", "Head", "Foot");
    verifyTextOnPage();
    returnToGroupsPage();
  //Once all your stuff done with this frame need to switch back to default
    driver.switchTo().defaultContent();
  

  @Test
  public void testAddNewEmptyGroup() throws Exception 
    openMainPage();
    findFrame();
    logIn();
    goToGroupPage();
    fillFormAndSubmit("", "", "");
    verifyTextOnPage();
    returnToGroupsPage();
  //Once all your stuff done with this frame need to switch back to default
    driver.switchTo().defaultContent();
  

private void verifyTextOnPage() 
    try 
      assertEquals("A new group has been entered into the address book.return to the group page", driver.findElement(By.xpath("//div[@id='content']/div")).getText());
     catch (Error e) 
      verificationErrors.append(e.toString());
    


private void returnToGroupsPage() 
    driver.findElement(By.linkText("group page")).click();


private void fillFormAndSubmit(String name, String header, String footer) 
    clickAndClear("group_name", "group_name");
    driver.findElement(By.name("group_name")).sendKeys(name);
    clickAndClear("group_header", "group_header");
    driver.findElement(By.name("group_header")).sendKeys(header);
    clickAndClear("group_footer", "group_footer");
    driver.findElement(By.name("group_footer")).sendKeys(footer);
    driver.findElement(By.name("submit")).click();


private void goToGroupPage() 
    driver.findElement(By.linkText("Группы")).click();
    driver.findElement(By.name("new")).click();


private void logIn() 
    driver.findElement(By.name("user")).clear();
    driver.findElement(By.name("user")).sendKeys("admin");
    driver.findElement(By.name("pass")).clear();
    driver.findElement(By.name("pass")).sendKeys("pass");
    driver.findElement(By.xpath("//input[@value='Войти']")).click();


private void findFrame() 
        WebDriverWait wait = new WebDriverWait(driver, 10);
        wait.until(ExpectedConditions.frameToBeAvailableAndSwitchToIt("demobody"));


private void openMainPage() 
    driver.get("https://www.softaculous.com/softaculous/demos/php_Address_Book");


private void clickAndClear(String locator, String locator2) 
    driver.findElement(By.name(locator)).click();
    driver.findElement(By.name(locator2)).clear();


  @After
  public void tearDown() throws Exception 
    driver.quit();
    String verificationErrorString = verificationErrors.toString();
    if (!"".equals(verificationErrorString)) 
      fail(verificationErrorString);
    
  

  @SuppressWarnings("unused")
private boolean isElementPresent(By by) 
    try 
      driver.findElement(by);
      return true;
     catch (NoSuchElementException e) 
      return false;
    
  

  @SuppressWarnings("unused")
private boolean isAlertPresent() 
    try 
      driver.switchTo().alert();
      return true;
     catch (NoAlertPresentException e) 
      return false;
    
  

  @SuppressWarnings("unused")
private String closeAlertAndGetItsText() 
    try 
      Alert alert = driver.switchTo().alert();
      String alertText = alert.getText();
      if (acceptNextAlert) 
        alert.accept();
       else 
        alert.dismiss();
      
      return alertText;
     finally 
      acceptNextAlert = true;
    
  

堆栈跟踪是这样的：

java.lang.AssertionError: org.junit.ComparisonFailure: expected:<...to the address book.[]return to the group ...> but was:<...to the address book.[
]return to the group ...>
    at org.junit.Assert.fail(Assert.java:88)
    at com.example.tests.AddGroupTests.tearDown(AddGroupTests.java:112)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.base/java.lang.reflect.Method.invoke(Unknown Source)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:33)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:115)
    at org.junit.vintage.engine.execution.RunnerExecutor.execute(RunnerExecutor.java:42)
    at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(Unknown Source)
    at java.base/java.util.stream.ReferencePipeline$3$1.accept(Unknown Source)
    at java.base/java.util.Iterator.forEachRemaining(Unknown Source)
    at java.base/java.util.Spliterators$IteratorSpliterator.forEachRemaining(Unknown Source)
    at java.base/java.util.stream.AbstractPipeline.copyInto(Unknown Source)
    at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(Unknown Source)
    at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(Unknown Source)
    at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(Unknown Source)
    at java.base/java.util.stream.AbstractPipeline.evaluate(Unknown Source)
    at java.base/java.util.stream.ReferencePipeline.forEach(Unknown Source)
    at org.junit.vintage.engine.VintageTestEngine.executeAllChildren(VintageTestEngine.java:83)
    at org.junit.vintage.engine.VintageTestEngine.execute(VintageTestEngine.java:74)
    at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:170)
    at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:154)
    at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:90)
    at org.eclipse.jdt.internal.junit5.runner.JUnit5TestReference.run(JUnit5TestReference.java:86)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:538)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:760)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:460)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:206)

尝试删除所有导入并一一修复红色问题，仍然存在故障。我看到消息：AssertionError，但无法定位问题。有什么建议？提前致谢

【问题讨论】：

你能分享一下实际的错误信息吗？

您正在尝试导入一个类的所有元素。您只能对静态导入或包执行此操作。

发布minimal reproducible example。请don't post screenshots of code。粘贴代码并正确格式化它。发布实际（完整）错误消息。

看起来您正在使用 Eclipse。删除所有导入。现在，您将在 Eclipse 无法识别的代码下看到许多红色波浪线。将鼠标悬停在一个上，您将看到一个带有快速修复的弹出窗口。单击导入相关库的快速修复。继续此过程，直到所有红色曲线消失。

您应该尝试调试您的 tearDown() 方法，因为查看您的屏幕截图时存在堆栈跟踪问题，并且在此添加行之后会导致您的问题出现此异常以获得正确答案。

【参考方案1】：

AssertionError 发生在断言（您要验证的东西）失败时。当您收到AssertionError 时，并不意味着您的代码失败，而是意味着您检查的条件不正确。

现在通常断言错误意味着你正在测试的东西有问题。但通常是因为您测试事物的方式有问题。

在您的示例中，堆栈跟踪很有帮助：

java.lang.AssertionError: org.junit.ComparisonFailure: expected:<...to the address 
book.[]return to the group ...> but was:<...to the address book.[
]return to the group ...>

您尝试比较两个字符串，但它们不同。有什么不同？它突出显示：在您预期的字符串中（verifyTextOnPage 测试中的"A new group has been entered into the address book.return to the group page"），“return”紧跟在点之后，没有空格。实际文本显然在它们之间有一个换行符（“return”继续在新行上）。这就是比较失败的原因，这就是您得到AssertionError 的原因。

请不要害怕错误消息并尝试理解它们：它们提供了有价值的信息。