How to Avoid SELECT * and Mock SQL Column Queries in Python

import sqlite3
from unittest.mock import Mock, patch


def get_user_emails(connection):
    """Fetch only the required columns instead of SELECT *."""
    cursor = connection.cursor()
    cursor.execute("SELECT email FROM users")
    return [row[0] for row in cursor.fetchall()]


def test_get_user_emails_specific_columns():
    mock_connection = Mock()
    mock_cursor = mock_connection.cursor.return_value
    mock_cursor.fetchall.return_value = [("alice@example.com",), ("bob@example.com",)]
    
    emails = get_user_emails(mock_connection)
    
    # Verify the exact SQL with explicit column names
    mock_cursor.execute.assert_called_with("SELECT email FROM users")
    assert emails == ["alice@example.com", "bob@example.com"]


if __name__ == "__main__":
    test_get_user_emails_specific_columns()
    print("All tests passed - query explicitly specifies columns, avoiding SELECT *")