RegEX to validate email

validate_email.py

# validate email addresses
def validate_email(email):
    pattern = r"(^(?!-|\.)([a-zA-Z0-9._%+-]+)@(?!-)[a-zA-Z0-9.-]+(?<=[a-zA-Z0-9])\.[a-zA-Z]{2,}$)"
    if re.match(pattern, email):
        return True
    else:
        return False


if __name__ == "__main__":
    # test email validation
    test_cases = [
        ("email@example.com", True),
        ("email123@example.com", True),
        ("my-email@example.com", True),
        ("my.email@example.com", True),
        ("my_email@example.com", True),
        ("email@123.com", True),
        ("email@example.co.uk", True),
        ("email@sub.example.com", True),
        ("email+me@example.com", True),
        ("a@b.com", True),
        ("email.example.com", False),
        ("email@", False),
        ("@example.com", False),
        ("my email@example.com", False),
        ("email@exa#mple.com", False),
        ("email@ex@ample.com", False),
        ("email@-example.com", False),
        ("email@example-.com", False),
        ("email@example", False),
        ("email@example.c", False),
        (".me@mail.com", False),
        ("-me@mail.com", False)
    ]
    for case in test_cases:
        assert validate_email(case[0]) is case[1]