Example.php

<?php
namespace Codeception;

use Traversable;

class Example implements \ArrayAccess, \Countable, \IteratorAggregate
{
    protected $data;

    public function __construct($data)
    {
        $this->data = $data;
    }

    #[\ReturnTypeWillChange]
    /**
     * Whether a offset exists
     * @link http://php.net/manual/en/arrayaccess.offsetexists.php
     * @param mixed $offset <p>
     * An offset to check for.
     * </p>
     * @return boolean true on success or false on failure.
     * </p>
     * <p>
     * The return value will be casted to boolean if non-boolean was returned.
     * @since 5.0.0
     */
    public function offsetExists($offset)
    {
        return array_key_exists($offset, $this->data);
    }

    #[\ReturnTypeWillChange]
    /**
     * Offset to retrieve
     * @link http://php.net/manual/en/arrayaccess.offsetget.php
     * @param mixed $offset <p>
     * The offset to retrieve.
     * </p>
     * @return mixed Can return all value types.
     * @since 5.0.0
     */
    public function offsetGet($offset)
    {
        if (!$this->offsetExists($offset)) {
            throw new \PHPUnit\Framework\AssertionFailedError("Example $offset doesn't exist");
        };
        return $this->data[$offset];
    }

    #[\ReturnTypeWillChange]
    /**
     * Offset to set
     * @link http://php.net/manual/en/arrayaccess.offsetset.php
     * @param mixed $offset <p>
     * The offset to assign the value to.
     * </p>
     * @param mixed $value <p>
     * The value to set.
     * </p>
     * @return void
     * @since 5.0.0
     */
    public function offsetSet($offset, $value)
    {
        $this->data[$offset] = $value;
    }

    #[\ReturnTypeWillChange]
    /**
     * Offset to unset
     * @link http://php.net/manual/en/arrayaccess.offsetunset.php
     * @param mixed $offset <p>
     * The offset to unset.
     * </p>
     * @return void
     * @since 5.0.0
     */
    public function offsetUnset($offset)
    {
        unset($this->data[$offset]);
    }

    #[\ReturnTypeWillChange]
    /**
     * Count elements of an object
     * @link http://php.net/manual/en/countable.count.php
     * @return int The custom count as an integer.
     * </p>
     * <p>
     * The return value is cast to an integer.
     * @since 5.1.0
     */
    public function count()
    {
        return count($this->data);
    }

    #[\ReturnTypeWillChange]
    /**
     * Retrieve an external iterator
     * @link http://php.net/manual/en/iteratoraggregate.getiterator.php
     * @return Traversable An instance of an object implementing <b>Iterator</b> or
     * <b>Traversable</b>
     * @since 5.0.0
     */
    public function getIterator()
    {
        return new \ArrayIterator($this->data);
    }
}