What steps should PHP developers take to test and validate their code before seeking help or confirmation from others?

Issue: Before seeking help from others, PHP developers should ensure they have thoroughly tested and validated their code to identify any errors or bugs. Code snippet:

// Example code snippet to validate user input
$user_input = $_POST['user_input'];

// Check if user input is not empty
if(!empty($user_input)) {
    // Validate user input using regex
    if(preg_match("/^[a-zA-Z0-9]+$/", $user_input)) {
        echo "User input is valid.";
    } else {
        echo "Invalid user input. Please enter alphanumeric characters only.";
    }
} else {
    echo "User input cannot be empty.";
}