@Test
  public void testSolving() {
    GridModel grid = new GridModel(4);

    GridFiller filler = new GridFiller(grid);
    filler.fillRandom(grid.getSize() * 3 / 2);
    grid.shuffle();

    ClusterManager cluster = new ClusterManager(new NullLog());
    GridModel solutionGrid = new GridModel();

    AStarSolverMkI solver = new AStarSolverMkI(grid, solutionGrid, cluster);
    solver.run();
    assertTrue(solutionGrid.isComplete());
  }