Groovy几乎100%兼容Java，因此您可以在Selenium documentation中找到处理警报的示例代码，关于WebDriver Sampler的细节，您需要将driver更改为WDS.browser
包含必要导入的示例代码：

import org.openqa.selenium.Alert
import org.openqa.selenium.By
import org.openqa.selenium.chrome.ChromeDriver
import org.openqa.selenium.support.ui.ExpectedConditions
import org.openqa.selenium.support.ui.WebDriverWait

import java.time.Duration

WDS.sampleResult.sampleStart()
WebDriverWait wait = new WebDriverWait(WDS.browser, Duration.ofSeconds(10))
WDS.browser.get("https://www.selenium.dev/documentation/webdriver/interactions/alerts/")
WDS.browser.findElement(By.linkText("See a sample confirm")).click()
wait.until(ExpectedConditions.alertIsPresent())
Alert alert = WDS.browser.switchTo().alert()
String text = alert.getText()
WDS.log.info("Alert text: " + text)
alert.dismiss()
WDS.log.info("Current page title: " + WDS.browser.getTitle())
WDS.sampleResult.sampleEnd()

和演示：

有关JMeter中Groovy脚本的更多信息：Apache Groovy: What Is Groovy Used For?