在使用testng和java的程序中，从另一个类调用方法时出现问题

1 月 Questions & Answers 152

我不熟悉使用selenium和java进行测试。试图自动化银行应用程序的登录功能：

在这个过程中，其中一个方法面临空指针异常

首先，我有两门课：

open（此类包括打开浏览器、使用凭据登录以及使用@BeforeMethod、@Test和@AfterMethod关闭浏览器的方法）
登录（包括包含凭证详细信息的方法）

我试图做的是在@Test注释下从类login调用类open的方法。有人能帮我解决下面的错误吗

班级开放：

package Jprogramming;

import java.util.concurrent.TimeUnit;

import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;
import org.testng.annotations.*;

public class open {
    WebDriver driver;

    @BeforeMethod
    public void link() {
        System.out.println("setting bank application");
        System.setProperty("webdriver.chrome.driver","E:\\Java_Work\\chromedriver_win32\\chromedriver.exe" );
        WebDriver driver = new ChromeDriver();
        driver.manage().timeouts().implicitlyWait(10,TimeUnit.SECONDS);
        driver.get("https://parabank.parasoft.com");
        driver.manage().window().maximize();
    }

    @Test
    public void credentials() {
        login la = new login(driver);
        la.username();
        la.password();
        la.login();
    }

    @AfterMethod
    public void teardown() {
        driver.quit();
    }
}

类登录：

package Jprogramming;

import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;

public class login {
    WebDriver driver;

    By username = By.name("username");
    By password = By.name("password");
    By login = By.xpath("//*[@id='loginPanel']/form/div[3]/input");

    public login(WebDriver driver) {
        this.driver=driver;
    }

    public void username() {
        driver.findElement(username).sendKeys("abc");
    }

    public void password() {
        driver.findElement(password).sendKeys("cba");
    }

    public void login() {
        driver.findElement(login).click();
    }
}

我看到以下错误：

 [RemoteTestNG] detected TestNG version 6.14.2
 setting bank application
 Starting ChromeDriver 2.45.615291 (ec3682e3c9061c10f26ea9e5cdcf3c53f3f74387) on port 47261
 Only local connections are allowed.
 May 06, 2019 1:53:42 PM org.openqa.selenium.remote.ProtocolHandshake createSession
 INFO: Detected dialect: OSS
 FAILED CONFIGURATION: @AfterMethod teardown
 java.lang.NullPointerException
    at Jprogramming.open.teardown(open.java:40)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:124)
    at org.testng.internal.MethodInvocationHelper.invokeMethodConsideringTimeout(MethodInvocationHelper.java:59)
    at org.testng.internal.Invoker.invokeConfigurationMethod(Invoker.java:455)
    at org.testng.internal.Invoker.invokeConfigurations(Invoker.java:222)
    at org.testng.internal.Invoker.invokeMethod(Invoker.java:643)
    at org.testng.internal.Invoker.invokeTestMethod(Invoker.java:716)
    at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:988)
    at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:125)        at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:109)
    at org.testng.TestRunner.privateRun(TestRunner.java:648)
    at org.testng.TestRunner.run(TestRunner.java:505)
    at org.testng.SuiteRunner.runTest(SuiteRunner.java:455)
    at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:450)
    at org.testng.SuiteRunner.privateRun(SuiteRunner.java:415)
    at org.testng.SuiteRunner.run(SuiteRunner.java:364)
    at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:52)
    at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:84)
    at org.testng.TestNG.runSuitesSequentially(TestNG.java:1208)
    at org.testng.TestNG.runSuitesLocally(TestNG.java:1137)
    at org.testng.TestNG.runSuites(TestNG.java:1049)
    at org.testng.TestNG.run(TestNG.java:1017)
    at org.testng.remote.AbstractRemoteTestNG.run(AbstractRemoteTestNG.java:114)
    at org.testng.remote.RemoteTestNG.initAndRun(RemoteTestNG.java:251)
    at org.testng.remote.RemoteTestNG.main(RemoteTestNG.java:77)

    FAILED: credentials
    java.lang.NullPointerException
        at Jprogramming.login.username(login.java:18)
        at Jprogramming.open.credentials(open.java:32)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
        at java.lang.reflect.Method.invoke(Unknown Source)
        at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:124)
        at org.testng.internal.Invoker.invokeMethod(Invoker.java:580)
        at org.testng.internal.Invoker.invokeTestMethod(Invoker.java:716)
        at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:988)
        at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:125)
        at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:109)
        at org.testng.TestRunner.privateRun(TestRunner.java:648)
        at org.testng.TestRunner.run(TestRunner.java:505)
        at org.testng.SuiteRunner.runTest(SuiteRunner.java:455)
        at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:450)
        at org.testng.SuiteRunner.privateRun(SuiteRunner.java:415)
        at org.testng.SuiteRunner.run(SuiteRunner.java:364)
        at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:52)
        at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:84)
        at org.testng.TestNG.runSuitesSequentially(TestNG.java:1208)
        at org.testng.TestNG.runSuitesLocally(TestNG.java:1137)
        at org.testng.TestNG.runSuites(TestNG.java:1049)
        at org.testng.TestNG.run(TestNG.java:1017)
        at org.testng.remote.AbstractRemoteTestNG.run(AbstractRemoteTestNG.java:114)
        at org.testng.remote.RemoteTestNG.initAndRun(RemoteTestNG.java:251)
        at org.testng.remote.RemoteTestNG.main(RemoteTestNG.java:77)


    ===============================================
        Default test
        Tests run: 1, Failures: 1, Skips: 0
        Configuration Failures: 1, Skips: 0
    ===============================================


    ===============================================
    Default suite
    Total tests run: 1, Failures: 1, Skips: 0
    Configuration Failures: 1, Skips: 0
    ===============================================

共 (2) 个答案

# 1 楼答案
这个答案是不正确的，而且是基于错误的假设。在这里留待背景

虽然我不能确定，但我相当确定@BeforeMethod在类的单独实例中运行，而不是@test

那么你能做些什么呢？以下任一选项都可能有效：
1. 使WebDriver static在所有实例中共享driver
```
static WebDriver driver;
```
2. 用@BeforeTest代替@BeforeMethod
我对第二种选择不太确定，如果你每次都想换一个新司机，那么一旦你进行了更多的测试，这可能就不是你真正想要的
# 2 楼答案
问题是，您正在将WebDriver分配给link()内的局部变量，而不是实例变量

换线
```
WebDriver driver = new ChromeDriver();
```
因为
```
driver = new ChromeDriver();
```

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在使用testng和java的程序中，从另一个类调用方法时出现问题

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# 2 楼答案