Found the answer to my specific problem. In real files of test cases (mine were in applications → tests → cases → models), the fixtures used were not automatically generated in the $ inventory variable.
, " ", , ( ) $fixture .
, account_types . , $fxtures, :
var $fixtures = array('whatever_fixtures_where_already_here', 'name_of_missing_fixture', 'name_of_another_missing_fixture');
Rob