public ConnectionNodeEditPart assertHasExecutionEdge(DiagramDocumentEditor editor, EditPart source, EditPart target) {
for (Object c : editor.getDiagramEditPart().getConnections()) {
if (c instanceof ConnectionNodeEditPart) {
ConnectionNodeEditPart connection = (ConnectionNodeEditPart) c;
EObject element = connection.resolveSemanticElement();
if (element instanceof ExecutionEdge) {
if (connection.getSource().equals(source) &&
connection.getTarget().equals(target))
return connection; // found it
}