// Prepare container parameters
String fieldName = "fileField";
container.setParameter(fieldName, file, "text/html");
container.setParameter("form_name", "form");
FileFieldPage page = container.testPage(FileFieldPage.class);
FileField field = page.getFileField();
// Perform tests
assertNotNull(field.getFileItem());
field.getFileItem().getName();
assertEquals(fieldName, field.getFileItem().getFieldName());