如何用Python实现Selenium WebDriver多场景登录测试用例？

Hey there! Since you've already nailed CASE-1 (valid username/password login), let's dive into building out the rest of those login test scenarios using Python and Selenium WebDriver. I'll use pytest for test organization—it's clean, scalable, and widely used in the Python testing space.

Prerequisites #

First, make sure you've got these installed:

• selenium (for WebDriver interactions)
• pytest (for test running and fixtures)
• A WebDriver executable matching your browser (e.g., ChromeDriver for Chrome, GeckoDriver for Firefox)

You can install the packages via pip:

pip install selenium pytest

Test Setup #

Let's start with a base fixture to handle WebDriver initialization and cleanup—this avoids repeating code across test cases:

import pytest
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

@pytest.fixture(scope="function")
def driver():
    # Initialize ChromeDriver (swap with Firefox() if you prefer)
    driver = webdriver.Chrome()
    driver.maximize_window()
    # Navigate to your login page—replace with your actual URL
    driver.get("https://your-login-page-url.com")
    yield driver
    # Cleanup: close the browser after each test
    driver.quit()

# Helper function to get login elements (adjust selectors to match your page!)
def get_login_elements(driver):
    return {
        "email_input": driver.find_element(By.ID, "email"),  # Replace with your email field selector
        "password_input": driver.find_element(By.ID, "password"),  # Replace with your password field selector
        "login_button": driver.find_element(By.ID, "login-btn"),  # Replace with your login button selector
        "error_message": WebDriverWait(driver, 10).until(
            EC.presence_of_element_located((By.CLASS_NAME, "error-message"))  # Replace with your error message selector
        )
    }

Test Cases Breakdown #

Now let's implement each test case one by one. Note: You'll need to adjust element selectors (like IDs, class names) to match your actual login page's HTML.

CASE-2: Both Email and Password Fields Are Empty #

def test_login_empty_credentials(driver):
    elements = get_login_elements(driver)
    # Click login without entering anything
    elements["login_button"].click()
    # Verify the expected error message (update this text to match your site's message)
    assert "Please enter your email and password" in elements["error_message"].text

CASE-3: Email Filled, Password Empty #

def test_login_empty_password(driver):
    elements = get_login_elements(driver)
    # Enter valid email (you can use a test email here)
    elements["email_input"].send_keys("test@example.com")
    # Click login without entering password
    elements["login_button"].click()
    # Verify error message for empty password
    assert "Please enter your password" in elements["error_message"].text

CASE-4: Email Empty, Password Filled #

def test_login_empty_email(driver):
    elements = get_login_elements(driver)
    # Enter valid password (use a test password here)
    elements["password_input"].send_keys("ValidPass123!")
    # Click login without entering email
    elements["login_button"].click()
    # Verify error message for empty email
    assert "Please enter your email" in elements["error_message"].text

CASE-5: Both Email and Password Are Invalid #

def test_login_invalid_both_credentials(driver):
    elements = get_login_elements(driver)
    # Enter invalid email and password
    elements["email_input"].send_keys("wrong-email@example.com")
    elements["password_input"].send_keys("WrongPass456!")
    elements["login_button"].click()
    # Verify error for invalid credentials
    assert "Invalid email or password" in elements["error_message"].text

CASE-6: Invalid Email, Valid Password #

def test_login_invalid_email_valid_password(driver):
    elements = get_login_elements(driver)
    # Enter invalid email but valid password
    elements["email_input"].send_keys("invalid-email@example.com")
    elements["password_input"].send_keys("ValidPass123!")
    elements["login_button"].click()
    # Verify error message (might be same as CASE-5, depending on your site)
    assert "Invalid email or password" in elements["error_message"].text

CASE-7: Invalid Email Format (e.g., Missing @ Symbol) #

Let's add this common edge case as CASE-7—testing an email that doesn't follow basic format rules:

def test_login_invalid_email_format(driver):
    elements = get_login_elements(driver)
    # Enter email without @ symbol
    elements["email_input"].send_keys("testexample.com")
    elements["password_input"].send_keys("ValidPass123!")
    elements["login_button"].click()
    # Verify format error message
    assert "Please enter a valid email address" in elements["error_message"].text

Running the Tests #

To run all these tests, just open your terminal, navigate to the directory with your test file, and run:

pytest login_tests.py -v

The -v flag gives you verbose output so you can see which tests passed/failed.

Key Notes #

• Element Selectors: Always use stable selectors (like IDs or data attributes) instead of XPath or class names that might change.
• Explicit Waits: I used WebDriverWait for the error message to ensure the element loads before we check its text—this prevents flaky tests.
• Test Isolation: Each test starts with a fresh browser instance (thanks to the function-scoped fixture), so one test's actions don't affect another.

内容的提问来源于stack exchange，提问作者klay123tw