Katalon、Playwright、Java：実際に聞かれた面接質問6選

// Example: Custom Keyword in Katalon Studio (Groovy)
package com.custom.keywords

import com.kms.katalon.core.annotation.Keyword
import com.kms.katalon.core.webui.keyword.WebUiBuiltInKeywords as WebUI
import org.openqa.selenium.WebElement

class SmartWaitKeywords {
    @Keyword
    def waitForElementClickable(WebElement element, int timeoutSeconds) {
        // Custom explicit wait wrapping raw WebDriver inside Katalon
        for (int i = 0; i < timeoutSeconds; i++) {
            if (element.isDisplayed() && element.isEnabled()) {
                return true
            }
            Thread.sleep(1000)
        }
        throw new RuntimeException("Element not clickable within ${timeoutSeconds}s")
    }
}

String uniqueEmail = faker.internet().safeEmailAddress("test_" + System.currentTimeMillis());

// Thread-safe DataProvider pattern in Java with TestNG
public class ThreadSafeDataDrivenTest {

    // Using ThreadLocal to guarantee data isolation across parallel worker threads
    private static final ThreadLocal<UserCredentials> currentCredentials = new ThreadLocal<>();

    @DataProvider(name = "userRoles", parallel = true)
    public Object[][] provideUserRoles() {
        return new Object[][] {
            { new UserCredentials("admin_01@company.com", "EncryptedPass1!", "ADMIN") },
            { new UserCredentials("editor_02@company.com", "EncryptedPass2!", "EDITOR") },
            { new UserCredentials("viewer_03@company.com", "EncryptedPass3!", "VIEWER") }
        };
    }

    @Test(dataProvider = "userRoles")
    public void testRoleAccessControl(UserCredentials credentials) {
        currentCredentials.set(credentials);
        try {
            // Test execution is isolated to the worker thread's credentials
            LoginPage loginPage = new LoginPage(getDriver());
            DashboardPage dashboard = loginPage.loginAs(currentCredentials.get());
            Assert.assertEquals(dashboard.getRoleBadge(), credentials.getExpectedRole());
        } finally {
            // Prevent memory leaks in long-running CI runners
            currentCredentials.remove();
        }
    }
}

Selenium WebDriver Architecture (HTTP REST Polling):
[Test Script] ──HTTP Request──► [ChromeDriver.exe] ──W3C WebDriver Protocol──► [Browser Process]
                                 (Extra Network Hop & Polling Latency)

Playwright Architecture (Direct WebSocket Multiplexing):
[Test Runner] ◄═════Single Bidirectional WebSocket (Chrome DevTools / CDP)═════► [Browser Process]
                     (Instant Event Streams, Zero Polling Overhead)

// Example: Multi-User Chat Test in Playwright (Single Test, Two Isolated Users)
import { test, expect } from '@playwright/test';

test('User A sends a message that User B receives in real time', async ({ browser }) => {
  // Create two completely isolated contexts inside one browser
  const aliceContext = await browser.newContext({ storageState: 'auth/alice.json' });
  const bobContext = await browser.newContext({ storageState: 'auth/bob.json' });

  const alicePage = await aliceContext.newPage();
  const bobPage = await bobContext.newPage();

  // Alice sends a message
  await alicePage.goto('/chat/general');
  await alicePage.fill('[data-testid="message-input"]', 'Hello Bob!');
  await alicePage.click('[data-testid="send-btn"]');

  // Bob receives it via WebSocket without polling
  await bobPage.goto('/chat/general');
  await expect(bobPage.locator('.chat-bubble').last()).toHaveText('Hello Bob!');

  await aliceContext.close();
  await bobContext.close();
});

// Clean Page Object Pattern demonstrating strict Encapsulation in Java
public class LoginPage {
    private final WebDriver driver;
    private final WebDriverWait wait;

    // Encapsulated locators: Never exposed publicly
    private final By emailInput = By.id("user_email");
    private final By passwordInput = By.id("user_password");
    private final By submitButton = By.cssSelector("button[type='submit']");
    private final By errorMessageBanner = By.className("alert-danger");

    public LoginPage(WebDriver driver) {
        this.driver = driver;
        this.wait = new WebDriverWait(driver, Duration.ofSeconds(10));
    }

    // Fluent API design: returns next Page Object
    public DashboardPage loginValid(String email, String password) {
        enterCredentials(email, password);
        wait.until(ExpectedConditions.elementToBeClickable(submitButton)).click();
        return new DashboardPage(driver);
    }

    public String getErrorMessage() {
        return wait.until(ExpectedConditions.visibilityOfElementLocated(errorMessageBanner)).getText();
    }

    private void enterCredentials(String email, String password) {
        wait.until(ExpectedConditions.visibilityOfElementLocated(emailInput)).sendKeys(email);
        driver.findElement(passwordInput).sendKeys(password);
    }
}

// Diagnosing and overcoming StaleElementReferenceException defensively
public class ElementActions {

    public static boolean clickWithRetry(WebDriver driver, By locator, int maxAttempts) {
        int attempts = 0;
        WebDriverWait wait = new WebDriverWait(driver, Duration.ofSeconds(5));

        while (attempts < maxAttempts) {
            try {
                WebElement element = wait.until(ExpectedConditions.elementToBeClickable(locator));
                element.click();
                return true;
            } catch (StaleElementReferenceException e) {
                attempts++;
                System.out.println("Encountered StaleElement on attempt " + attempts + ", retrying...");
            }
        }
        throw new NoSuchElementException("Failed to click element after " + maxAttempts + " attempts: " + locator);
    }
}