什么是TestNG？

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>selenium_testng</groupId>
  <artifactId>selenium_testng</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <build>
    <sourceDirectory>src</sourceDirectory>
    <plugins>
      <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.8.1</version>
        <configuration>
          <release>16</release>
        </configuration>
      </plugin>
    </plugins>
  </build>
   <dependencies>
  	<dependency>
  		<groupId>org.seleniumhq.selenium</groupId>
  		<artifactId>selenium-java</artifactId>
  		<version>3.141.59</version>
  	</dependency>
  	<dependency>
            <groupId>org.testng</groupId>
            <artifactId>testng</artifactId>
            <version>7.1.0</version>
            <scope>test</scope>
        </dependency>
  </dependencies>
</project>

package test;

import org.testng.annotations.Test;

public class VerifySetup {

	@Test
	public void verifySetup()
	{
		System.out.println("TestNG setup is working fine");
	}
}

package test;

import org.testng.annotations.Test;

public class UnAnnotatedTestExample {

	@Test
	public void testWithAnnotation() 
	{
		System.out.println("This test is annotated");
	}

	public void testWithoutAnnotation() 
	{
		System.out.println("This test is not annotated");
	}
}

package test;
import org.testng.annotations.AfterClass;
import org.testng.annotations.AfterMethod;
import org.testng.annotations.AfterSuite;
import org.testng.annotations.AfterTest;
import org.testng.annotations.BeforeClass;
import org.testng.annotations.BeforeMethod;
import org.testng.annotations.BeforeSuite;
import org.testng.annotations.BeforeTest;
import org.testng.annotations.Test;
 
 
public class TestNGAnnotationsHierarchy {
 @Test
 public void testCase1() {
   System.out.println("This is Test Case 1"); 
 }
 
 @Test
 public void testCase2() {
   System.out.println("This is Test Case 2"); 
 }

 @BeforeMethod
 public void beforeMethod() {
   System.out.println("This will execute before every Test Method");
 }
 
 @AfterMethod
 public void afterMethod() {
   System.out.println("This will execute after every Test Method");
 }
 
 @BeforeClass
 public void beforeClass() {
   System.out.println("This will execute before the Class");
 }
 
 @AfterClass
 public void afterClass() {
   System.out.println("This will execute after the Class");
 }
 
 @BeforeTest
 public void beforeTest() {
   System.out.println("This will execute before the First Test");
 }
 
 @AfterTest
 public void afterTest() {
   System.out.println("This will execute after the Last Test");
 }
 
 @BeforeSuite
 public void beforeSuite() {
   System.out.println("This will execute before the Test Suite");
 }
 
 @AfterSuite
 public void afterSuite() {
   System.out.println("This will execute after the Test Suite");
 }
}

package test;

import org.testng.annotations.AfterGroups;
import org.testng.annotations.BeforeGroups;
import org.testng.annotations.Test;

public class TestNGAttributesExample {

	@Test(enabled = false, description = "This test will be skipped as enabled is set to false")
	public void disabledTest() {
		System.out.println("This method will be skipped from the test run using the attribute enabled=false");
	}

	@Test(invocationCount = 5, invocationTimeOut = 20, groups = "testngAttributes")
	public void invocationCountTest() {
		System.out.println("This method will be executed by 5 times");
	}

	@Test(timeOut = 500, groups = "testngAttributes")
	public void baseTest() {
		System.out.println("This is base test method");
	}

	@Test(dependsOnMethods = "baseTest", groups = "testngAttributes")
	public void firstDependentTest() {
		System.out.println("This is dependent method 1 and will only execute if baseTest passes");
	}

	@Test(alwaysRun = true, dependsOnMethods = "baseTest", groups = "testngAttributes")
	public void secondDependentTest() {
		System.out.println(
				"This is dependent method 2 and will execute irrespective of baseTest result because of alwaysRun");
	}

	@BeforeGroups("testngAttributes")
	public void beforeGroupMethod() {
		System.out.println("This method is executed before testngAttributes group test cases");
	}

	@AfterGroups("testngAttributes")
	public void afterGroupMethod() {
		System.out.println("This method is executed after testngAttributes group test cases");
	}
}

package test;

import org.testng.annotations.Test;

public class TestNGPrioritiesExample {
	@Test(priority = 1)
	public void aTest() {
		System.out.println("This is test a.");
	}

	@Test(priority = 2)
	public void bTest() {
		System.out.println("This is test b.");
	}

	@Test
	public void cTest() {
		System.out.println("This is test c.");
	}

	@Test(priority = 1)
	public void dTest() {
		System.out.println("This is test d.");
	}

	@Test
	public void eTest() {
		System.out.println("This is test e.");
	}

}

@DataProvider(name = "dataProvider_name")
public Object[][] dataProviderMethod() {
return new Object[][] {<values>};
}

package test;

import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.testng.annotations.DataProvider;
import org.testng.annotations.Test;

public class DataProviderExample {

	@DataProvider(name = "browserName")
	public Object[][] browserName() 
	{
		return new Object[][] { { "chrome" }, { "firefox" } };
	}

	@Test(dataProvider = "browserName")
	public void crossBrowserTest(String browser) 
	{
		WebDriver driver = null;
		
		System.out.println("Launching browser : " + browser);
		
		switch(browser)
		{
			case "chrome":
				System.setProperty("webdriver.chrome.driver", "<Path_to_your_chrome_driver>");
				driver = new ChromeDriver();
				break;
			case "firefox":
				System.setProperty("webdriver.firefox.driver", "<Path_to_your_firefox_driver>");
				driver = new FirefoxDriver();
				break;
			default:
				System.out.println("Invalid browser name passed");
		}
		
		driver.navigate().to("http://www.taobao.com/");
		System.out.println("Navigated Successfully to the website");
	}

}

Assert.Method(actual, expected, message)

package test;

import java.net.MalformedURLException;
import java.net.URL;
import org.openqa.selenium.By;
import org.openqa.selenium.remote.*;
import org.testng.Assert;
import org.testng.annotations.*;

public class SeleniumTestNGExample {

	public RemoteWebDriver driver = null;
	String username = "<lambdatest_username>";
	String accessKey = "<lambdatest_accesskey>";

	@BeforeSuite
	public void setUp() {
		DesiredCapabilities capabilities = new DesiredCapabilities();
		capabilities.setCapability("browserName", "Chrome");
		capabilities.setCapability("version", "92.0");
		capabilities.setCapability("platform", "Windows 10");
		capabilities.setCapability("resolution", "1024x768");
		capabilities.setCapability("build", "TestNG Selenium Tutorial");
		capabilities.setCapability("name", "TestNG Selenium JAVA");

		try {
			driver = new RemoteWebDriver(
					new URL("https://" + username + ":" + accessKey + "@hub.lambdatest.com/wd/hub"), capabilities);
		} catch (MalformedURLException e) {
			System.out.println("Invalid grid URL");
		}
		System.out.println("The driver setup process is completed using BeforeSuite");
	}

	@BeforeTest
	public void browserProfile() {
		driver.manage().window().maximize();
		System.out.println("The browser profile is updated using BeforeTest");

	}

	@BeforeClass
	public void navigateToUrl() {
		driver.get("https://www.lambdatest.com/selenium-playground/simple-form-demo");
		System.out.println("Navigated to URL using BeforeClass");
	}

@Test(description = "Test case with priority", priority = 1)
	public void testPriotity()
	{
		System.out.println("This case has priority 1");
	}
	
	@Test(description = "Test case with priority and invocation count", priority = 2, invocationCount = 2)
	public void testInvocationCount()
	{
		System.out.println("This case has priority 2 and invocation count");
	}

	@DataProvider(name = "SanityTestData")
	public Object[][] sanityTestDataProvider() {
		String[][] testData = { { "1", "4", "5" }, { "2", "4", "7" } };
		return testData;
	}

	@Test(dataProvider = "SanityTestData", description = "Test case with group and data provider but without priority
", alwaysRun = true, groups = { "sanity" })
	public void testSumOfTwoValues(String firstValue, String secondValue, String expectedSum) {
		// to enter data and submit
		driver.findElement(By.id("sum1")).sendKeys(firstValue);
		driver.findElement(By.id("sum2")).sendKeys(secondValue);
		driver.findElement(By.xpath("//button[text()='Get values']")).click();

		// to fetch actual result
		String actualSum = driver.findElement(By.id("addmessage")).getText();

		// to assert actual and expected result
		Assert.assertEquals(actualSum, expectedSum,
				"Expected and actual results do not match. Expected : " + expectedSum + " and Actual : " + actualSum);

	}

	@AfterMethod()
	public void clearOldData() {
		driver.findElement(By.id("sum1")).clear();
		driver.findElement(By.id("sum2")).clear();
	}

	@AfterClass
	public void closeDriver() {
		driver.quit();
		System.out.println("Quit the driver using AfterClass");
	}

	@AfterTest
	public void testReporting() {
		System.out.println("Test Report generated using AfterTest");
	}
}