 assertClassList(getContainerCell(grid.$.items, 1, 1), ['foo']);
      });

      it('should add all classes separated by whitespaces', () => {
        grid.cellClassNameGenerator = (column, model) => 'foo bar baz';
        assertClassList(firstCell, ['foo', 'bar', 'baz']);
      });

      it('should not remove existing classes', () => {
        firstCell.classList.add('bar');
        grid.cellClassNameGenerator = (column, model) => 'foo';
        assertClassList(firstCell, ['bar', 'foo']);
      });

    