### Question:
DMNGridHelper { public Set<GridWidget> getGridWidgets() { return getDefaultGridLayer() .getGridWidgets() .stream() .filter(Objects::nonNull) .collect(Collectors.toSet()); } @Inject  DMNGridHelper(final SessionManager sessionManager); void highlightCell(final int row,
                              final int column,
                              final GridWidget gridWidget); void focusGridPanel(); void clearSelections(); void clearCellHighlights(); Set<GridWidget> getGridWidgets();  }### Answer:
@Test public void getGridWidgets() { when(defaultGridLayer.getGridWidgets()).thenReturn(asSet(gridWidget1, null, gridWidget2, null, gridWidget3)); final Set<GridWidget> actualGridWidgets = helper.getGridWidgets(); final Set<GridWidget> expectedGridWidgets = asSet(gridWidget1, gridWidget2, gridWidget3); assertEquals(expectedGridWidgets, actualGridWidgets); }