@Test
public void testGenerate() {
SudokuModel model = new SudokuModel(2);
Map<String, Object> assignment = new HashMap<String, Object>();
boolean sat = new Z3Executor().execute(model, assignment);
assertTrue(sat);
for (Entry<String, Object> assign : assignment.entrySet()) {
System.out.println(MessageFormat.format("{0}={1}", assign.getKey(),
assign.getValue()));