### Question:
LabeledTextField extends HBox implements FxmlView<LabeledTextFieldViewModel> { @FXML public void onAction() { viewModel.changeLabel(); } LabeledTextField(); void initialize(); @FXML void onAction();  }### Answer:
@Test public void testOnAction() { assertThat(viewModel.labelTextProperty()).hasValue("default"); viewModel.inputTextProperty().set("hello"); assertThat(viewModel.labelTextProperty()).hasValue("default"); viewModel.changeLabel(); assertThat(viewModel.labelTextProperty()).hasValue("hello"); assertThat(viewModel.inputTextProperty()).hasValue(""); }