Parses the content, search for the form and assign respective elements to array keys as `formAction`, 'formId', 'formMethod' that can be checked against for easy assertions. When multiple forms are found they will be stored on arrays with key 'availableForms'.

available_forms.php

<?php

/**
 * Parses the content, search for the form and assign respective elements to
 * array keys as 'formAction', 'formId', 'formMethod' that can be checked against
 * for easy assertions. When multiple forms are found they will be stored on
 * arrays with key 'availableForms'.
 *
 * @param  string  $content HTML content for the form
 *
 * @return  array  respective form attribute associations keys
 */
public static function extractFormInformation(string $content) : array
{
    $dom = new DOMDocument('1.0', 'utf-8');

    // Reports error on HTML5 tags so temporarily suppress error to load DOM
    libxml_use_internal_errors(true);
    $dom->loadHTML($content);
    libxml_use_internal_errors(false);

    $forms = $dom->getElementsByTagName('form');

    // array of minimal available attributes in the form
    $attrFilters = [
        'action', 'id', 'method', 'name', 'class'
    ];

    $availableForms = [];

    foreach ($forms as $idx => $formElement) {
        foreach ($formElement->attributes as $attr) {
            if (in_array($attr->nodeName, $attrFilters)) {
                $variable                        = 'form' . studly_case($attr->nodeName);
                $availableForms[$idx][$variable] = $attr->nodeValue;
            }
        }
    }

    array_walk($attrFilters, function (&$value) {
        $value = 'form' . ucfirst($value);
    });

    return compact($attrFilters, 'availableForms');
}