// if this is actually an ErrorEditPart, then an error has occured
// (but it may not be obvious in the log what it is)
assertTrue("active editor is our plugin, but is " + ep, ep instanceof IamlDiagramEditor);
// find what elements are displayed
IamlDiagramEditor editor = (IamlDiagramEditor) ep;
// there should be four children
assertEditorHasChildren(4, editor);
// check the contents