How to test an email address input field?

The email address input field testing includes checks:

• Format validation:
  • Correct formats (name@domain.zone, name.surname@subdomain.domain.zone, etc.).
  • Incorrect formats (missing @, no domain, multiple @, forbidden characters, spaces).
  • Special characters in local part and domain.
  • Domain names of various lengths.
  • IP address as domain (user@[192.168.1.1]).
• Field length:
  • Minimum allowed length.
  • Maximum allowed length.
  • Exceeding maximum length.
• Field mandatory:
  • Submitting form with empty field.
• Case sensitivity:
  • Is the field case-sensitive (usually no for domain part).
• Cross-browser and cross-platform testing:
  • Correct display and behavior across different browsers and devices.
• Security testing:
  • XSS attacks (script input).
  • SQL injections (if the field interacts directly with a database).
• Performance:
  • Response time when entering long/complex addresses (if real-time validation is enabled).

Test case examples:

ID	Test case description	Input data	Expected result	Actual result	Status
TC-001	Valid email format	test@example.com	System accepts email, no error message.
TC-002	Invalid format (missing @)	testexample.com	System displays format error message.
TC-003	Invalid format (multiple @)	test@example@com	System displays format error message.
TC-004	Empty field (mandatory)	(empty)	System displays message that the field is required.
TC-005	Long email	a*250 + @example.com	System correctly handles an email of permissible length.

Example of automated test (Python with Selenium):

# test_email_field.py
from selenium import webdriver
from selenium.webdriver.common.by import By

def test_valid_email_input():
    driver = webdriver.Chrome() # or another driver
    driver.get("http://your-app-url.com") # replace with your app URL

    email_field = driver.find_element(By.ID, "email") # replace with your field locator
    email_field.send_keys("test@example.com")

    # Check for absence of error message
    error_message = driver.find_elements(By.ID, "email-error") # replace with your error message locator
    assert len(error_message) == 0, "Error message appeared for correct email"

    driver.quit()

def test_invalid_email_input():
    driver = webdriver.Chrome()
    driver.get("http://your-app-url.com")

    email_field = driver.find_element(By.ID, "email")
    email_field.send_keys("invalid-email")

    # Check for error message display
    error_message = driver.find_element(By.ID, "email-error") # replace with your error message locator
    assert error_message.is_displayed(), "Error message did not appear for incorrect email"

    driver.quit()