Once MDL-81750 is merged
append to /lib/form/tests/behat/disabledif.feature the following scenario:

  @_file_upload
  Scenario: The file manager added using addGroup can be found using standard methods
    Given I am on fixture page "/lib/form/tests/behat/fixtures/filemanager_hideif_disabledif_form.php"
    And I upload "mod/assign/feedback/editpdf/fixtures/blank.pdf" file to "Standard filemanager" filemanager
    And I upload "mod/assign/feedback/editpdf/fixtures/blank.pdf" file to "Group filemanager" filemanager

Run it.

The file blank.pdf is correctly loaded to "Standard filemanager" filemanager
but the second filemanager element is not seen.

I get the error:

001 Scenario: The file manager added using addGroup can be found using standard methods                     # /Applications/MAMP/htdocs/m404/lib/form/tests/behat/disabledif.feature:19
      And I upload "mod/assign/feedback/editpdf/fixtures/blank.pdf" file to "Group filemanager" filemanager # /Applications/MAMP/htdocs/m404/lib/form/tests/behat/disabledif.feature:22
        "Group filemanager" filepicker can not be found (Behat\Mink\Exception\ExpectationException)