### Question:
UndefinedExpressionUIModelMapper extends BaseUIModelMapper<Expression> { @Override public void fromDMNModel(final int rowIndex, final int columnIndex) { uiModel.get().setCell(rowIndex, columnIndex, () -> new UndefinedExpressionCell(listSelector, translationService)); } UndefinedExpressionUIModelMapper(final Supplier<GridData> uiModel,
                                            final Supplier<Optional<Expression>> dmnModel,
                                            final ListSelectorView.Presenter listSelector,
                                            final TranslationService translationService,
                                            final HasExpression hasExpression); @Override void fromDMNModel(final int rowIndex,
                             final int columnIndex); @Override void toDMNModel(final int rowIndex,
                           final int columnIndex,
                           final Supplier<Optional<GridCellValue<?>>> cell);  }### Answer:
@Test public void testFromDMNModel() { mapper.fromDMNModel(0, 0); assertThat(mapper.getUiModel().get().getCell(0, 0)).isInstanceOf(UndefinedExpressionCell.class); }