oi

```python
# File: src/utils/email_validator.py
# Description: Validates email format and checks for disposable domains
# Dependencies: re, typing, pytest
# Standards: PEP 8, Project Email Validation Spec v2.1

from typing import Optional
import re

# Disposable email domain list (last updated: 2024-05-15)
DISPOSABLE_DOMAINS = {
    "mailinator.com", "tempmail.com", "guerrillamail.com", 
    "10minutemail.com", "throwawaymail.com"
}


def validate_email(email: str) -> tuple[bool, Optional[str]]:
    """
    Validates an email address format and checks against disposable domains.
    
    Args:
        email: The email address to validate
        
    Returns:
        tuple: (is_valid, error_message)
               is_valid: True if email is valid and not disposable
               error_message: None if valid, otherwise specific error
    """
    # Basic format validation
    pattern = r'^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$'
    if not re.match(pattern, email):
        return False, "Invalid email format"
    
    # Extract domain
    _, domain = email.split('@', 1)
    
    # Check for disposable domains
    if domain.lower() in DISPOSABLE_DOMAINS:
        return False, "Disposable email domain detected"
    
    # Check for role-based emails (admin@, support@, etc.)
    local_part = email.split('@')[0]
    if local_part.lower() in {"admin", "support", "info", "contact"}:
        return False, "Role-based email addresses are not accepted"
    
    return True, None


def test_validate_email():
    """Unit tests for email validation function"""
    import pytest
    
    test_cases = [
        ("[email protected]", True, None),
        ("invalid-email", False, "Invalid email format"),
        ("[email protected]", False, "Disposable email domain detected"),
        ("[email protected]", False, "Role-based email addresses are not accepted"),
        ("[email protected]", True, None),
        ("", False, "Invalid email format"),
        ("user@localhost", False, "Invalid email format")
    ]
    
    for email, expected_valid, expected_error in test_cases:
        is_valid, error = validate_email(email)
        assert is_valid == expected_valid, f"Failed for {email}"
        assert error == expected_error, f"Failed for {email}"
    
    print("All tests passed!")


if __name__ == "__main__":
    test_validate_email()
```