Upload a file

Consider the following <input> html element.

<input type='file' id='file_input'></input>

<?php
  // getting the input element
  $file_input = $driver->findElement(
    WebDriverBy::id('file_input')
  );

  // set the file detector
  $file_input->setFileDetector(new LocalFileDetector());

  // upload the file and submit the form
  $file_input->sendKeys($file_path)->submit();

That's all. :D