DataSet ds2 = createDataSet(new SelectItem[] { si5, si6, si7 }, data2);
FilterItem[] onConditions = new FilterItem[1];
onConditions[0] = new FilterItem(si4, OperatorType.EQUALS_TO, si5);
DataSet result = MetaModelHelper.getLeftJoin(ds1, ds2, onConditions);
List<Object[]> objectArrays = result.toObjectArrays();
assertEquals("[1, peter, 18, 1, 1, class president, clpr]", Arrays.toString(objectArrays.get(0)));
assertEquals("[2, tom, 19, 2, 2, bad boy, bb]", Arrays.toString(objectArrays.get(1)));
assertEquals("[3, betty, 19, null, null, null, null]", Arrays.toString(objectArrays.get(2)));
assertEquals("[4, barbara, 17, 3, null, null, null]", Arrays.toString(objectArrays.get(3)));
assertEquals("[5, susie, 18, 4, 4, trying harder, try]", Arrays.toString(objectArrays.get(4)));