selenium

## When to use this skill

Use this skill whenever the user wants to:
- Write or maintain browser automation tests with Selenium WebDriver
- Locate elements using CSS selectors, IDs, or relative locators
- Implement explicit and implicit waits for robust test execution
- Run tests in headless mode or across browsers via Selenium Grid
- Integrate Selenium tests into CI/CD pipelines

## How to use this skill

### Workflow

1. **Set up the environment**: install browser drivers (ChromeDriver/GeckoDriver) or use Selenium 4 Manager
2. **Write test scripts**: navigate, find elements, interact, and assert
3. **Add waits and error handling**: use explicit waits instead of `sleep`
4. **Run in CI**: configure headless mode or Grid; generate reports

### 1. Basic Test (Python)

```python
from selenium import webdriver
from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC

driver = webdriver.Chrome()
driver.get("https://example.com/login")

# Explicit wait for element
wait = WebDriverWait(driver, 10)
username = wait.until(EC.presence_of_element_located((By.ID, "username")))
username.send_keys("testuser")

driver.find_element(By.ID, "password").send_keys("secret")
driver.find_element(By.CSS_SELECTOR, "button[type='submit']").click()

# Assert login success
assert "Dashboard" in driver.title

driver.quit()
```

### 2. Basic Test (Java)

```java
WebDriver driver = new ChromeDriver();
driver.get("https://example.com/login");

WebDriverWait wait = new WebDriverWait(driver, Duration.ofSeconds(10));
WebElement username = wait.until(ExpectedConditions.presenceOfElementLocated(By.id("username")));
username.sendKeys("testuser");

driver.findElement(By.id("password")).sendKeys("secret");
driver.findElement(By.cssSelector("button[type='submit']")).click();

assertTrue(driver.getTitle().contains("Dashboard"));
driver.quit();
```

### 3. Headless Mode

```python
from selenium.webdriver.chrome.options import Options

options = Options()
options.add_argument("--headless")
options.add_argument("--no-sandbox")
driver = webdriver.Chrome(options=options)
```

## Best Practices

- Use explicit waits (`WebDriverWait`) instead of `time.sleep` for reliable tests
- Prefer ID, CSS selector, or relative locators over fragile XPath expressions
- Keep test cases independent and repeatable; capture screenshots on failure
- Store sensitive data (URLs, credentials) in configuration files or environment variables
- Use Selenium Grid for parallel execution; ensure browser and driver versions match

## Resources

- Official documentation: https://www.selenium.dev/documentation/
- Selenium Grid: https://www.selenium.dev/documentation/grid/

## Keywords

selenium, WebDriver, browser automation, E2E, end-to-end testing, headless, Selenium Grid, ChromeDriver, explicit wait, CSS selector