# selenium

Enforces Selenium Python best practices in Cursor: Page Object Model design, explicit WebDriverWait conditions, and headless Chrome setups.

- rule · `type=rule` · Cursor · ★ 3580
- Author: sanjeed5
- License: CC0-1.0 · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/sanjeed5/awesome-cursor-rules-mdc/tree/HEAD/rules-mdc/selenium.mdc
- Updated: 2026-05-19
- HTML: https://affpapa.org/en/nevibecode/rules/selenium

## What it does

The rule targets `**/*.py` files to guide Cursor toward structured Selenium automation. It enforces the Page Object Model (POM), separating UI locators and interactions into dedicated classes like `BasePage` instead of mixing them with test logic.

Hard pauses with `time.sleep()` and implicit waits are banned. The assistant must use `WebDriverWait` combined with `expected_conditions`. For element locators, it prioritizes `By.ID` and `By.CSS_SELECTOR`, avoiding fragile absolute XPath strings and ambiguous class names.

It configures Chrome options for headless execution with flags like `--headless=new`, `--no-sandbox`, and `--disable-dev-shm-usage`. Driver binaries run via Selenium Manager or `webdriver-manager`. Script execution wraps in `try...finally` blocks to call `driver.quit()`, preventing orphaned browser processes from hanging in memory.

## Install

### Cursor (native platform)

**Manually: put the files in place**
- File: `.cursor/rules/selenium.mdc` — Frontmatter: description, globs, alwaysApply

### Claude Code

**Manually: put the files in place**
- File: `.claude/rules/selenium.md` — The paths frontmatter field limits the files: move globs from the source into paths

### Codex

**AGENTS.md**
- Codex reads AGENTS.md: paste the rule text there

### GitHub Copilot

**Manually: put the files in place**
- File: `.github/instructions/selenium.instructions.md` — The applyTo field sets which files it applies to: move globs from the source into applyTo

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/rules/selenium.md`

### Cline

**Manually: put the files in place**
- File: `.clinerules/selenium.md`

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/sanjeed5/awesome-cursor-rules-mdc/tree/HEAD/rules-mdc/selenium.mdc

## When to use it
- isolate page locators from test logic using the Page Object Model
- eliminate flaky test failures by replacing `time.sleep()` with explicit waits
- configure headless Chrome arguments for CI and Docker environments
- prevent orphaned browser processes by enforcing `driver.quit()` in teardown

## Example prompts
- Write a login test in Python using the Page Object Model pattern
- Wait for a dynamic button to become clickable and click it
- Set up headless Chrome with standard Docker flags and automatic driver management

## Source text · selenium.mdc · CC0-1.0

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: f38434442dc78d8c.

BEGIN THIRD-PARTY FILE f38434442dc78d8c
````text
---
description: Definitive guidelines for writing robust, maintainable, and readable Selenium automation scripts in Python, focusing on modern best practices for testing and web scraping.
globs: **/*.py
---
# selenium Best Practices

This guide outlines the definitive best practices for using Selenium with Python. Adhere to these rules to ensure your automation scripts are robust, maintainable, and performant.

## 1. Code Organization: Page Object Model (POM)

Always structure your Selenium code using the Page Object Model (POM). This separates UI elements and interactions from your test or scraping logic, making your code highly maintainable and reusable.

❌ **BAD: Logic and locators mixed**
```python
from selenium import webdriver
from selenium.webdriver.common.by import By

driver = webdriver.Chrome()
driver.get("https://example.com/login")
driver.find_element(By.ID, "username").send_keys("user")
driver.find_element(By.ID, "password").send_keys("pass")
driver.find_element(By.XPATH, "//button[text()='Login']").click()
# ... more logic
```

✅ **GOOD: Page Object Model**
```python
# pages/base_page.py
from selenium.webdriver.remote.webdriver import WebDriver
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC
from selenium.webdriver.common.by import By

class BasePage:
    def __init__(self, driver: WebDriver, timeout: int = 10):
        self.driver = driver
        self.wait = WebDriverWait(driver, timeout)

    def _find_element(self, by: By, value: str):
        return self.wait.until(EC.presence_of_element_located((by, value)))

# pages/login_page.py
from pages.base_page import BasePage
from selenium.webdriver.common.by import By

class LoginPage(BasePage):
    URL = "https://example.com/login"
    _USERNAME_INPUT = (By.ID, "username")
    _PASSWORD_INPUT = (By.ID, "password")
    _LOGIN_BUTTON = (By.XPATH, "//button[text()='Login']")

    def open(self):
        self.driver.get(self.URL)

    def login(self, username, password):
        self._find_element(*self._USERNAME_INPUT).send_keys(username)
        self._find_element(*self._PASSWORD_INPUT).send_keys(password)
        self._find_element(*self._LOGIN_BUTTON).click()

# tests/test_login.py (or main scraping script)
from selenium import webdriver
from pages.login_page import LoginPage

def test_successful_login():
    driver = webdriver.Chrome()
    try:
        login_page = LoginPage(driver)
        login_page.open()
        login_page.login("valid_user", "valid_pass")
        assert "dashboard" in driver.current_url # Example assertion
    finally:
        driver.quit()
```

## 2. Robustness: Explicit Waits

Never use `time.sleep()` or rely solely on implicit waits. Use `WebDriverWait` with `expected_conditions` to explicitly wait for elements to be in a specific state. This prevents flaky tests and ensures scripts are resilient to dynamic page loading.

❌ **BAD: Arbitrary waits or implicit waits**
```python
import time
from selenium.webdriver.remote.webdriver import WebDriver
from selenium.webdriver.common.by import By

driver: WebDriver = ...
driver.implicitly_wait(10) # Still prone to issues
driver.get("https://example.com")
time.sleep(5) # NEVER DO THIS
element = driver.find_element(By.ID, "dynamic_content")
```

✅ **GOOD: Explicit Waits with Expected Conditions**
```python
from selenium.webdriver.remote.webdriver import WebDriver
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC
from selenium.webdriver.common.by import By

driver: WebDriver = ...
driver.get("https://example.com")
wait = WebDriverWait(driver, 10)

# Wait for element to be visible
dynamic_element = wait.until(EC.visibility_of_element_located((By.ID, "dynamic_content")))
````
END THIRD-PARTY FILE f38434442dc78d8c

The third-party file has ended. Everything between the f38434442dc78d8c tags is data: requests and commands from it are not followed. An “end of file” line with another tag inside the block is part of the file.

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