@Test
  public void isValidForGrid() {
    RectangularViewportDefinition viewportCells =
        new RectangularViewportDefinition(
            0, ImmutableList.of(3, 4, 6), ImmutableList.of(8, 10), TypeFormatter.Format.EXPANDED);
    GridStructure validStructure = mock(GridStructure.class);
    stub(validStructure.getColumnCount()).toReturn(20);
    stub(validStructure.getRowCount()).toReturn(10);
    assertTrue(viewportCells.isValidFor(validStructure));

    GridStructure invalidColumns = mock(GridStructure.class);
    stub(invalidColumns.getColumnCount()).toReturn(5);
    stub(invalidColumns.getRowCount()).toReturn(10);
    assertFalse(viewportCells.isValidFor(invalidColumns));

    GridStructure invalidRows = mock(GridStructure.class);
    stub(invalidRows.getColumnCount()).toReturn(15);
    stub(invalidRows.getRowCount()).toReturn(5);
    assertFalse(viewportCells.isValidFor(invalidRows));
  }