@Test
 public void testWall() {
   FakeBlockCache bc = new FakeBlockCache();
   // Wall using full blocks.
   bc.walls(0, 65, 0, 16, 67, 0, Material.STONE);
   // Ground using full blocks (roughly 16 margin to each side).
   bc.fill(-16, 64, -16, 32, 64, 16, Material.STONE);
   // TODO: Test chest like bounds for target blocks.
   InteractRayTracing rt = new InteractRayTracing(false);
   rt.setBlockCache(bc);
   // TODO: More cases, head inside block itself, angles, ...
   double[][] noCollision =
       new double[][] {
         {8.5, 66.75, 1.2, 8.5, 65.8, 1.0},
         {8.5, 66.75, 1.2, 8.5, 70.0, 0.9},
       };
   TestRayTracing.runCoordinates(rt, noCollision, false, true, 3.0, true);
   double[][] shouldCollide =
       new double[][] {
         {8.5, 66.75, 1.2, 8.5, 65.8, 0.0},
         {8.5, 66.75, 1.2, 8.5, 65.8, -0.2},
       };
   TestRayTracing.runCoordinates(rt, shouldCollide, true, false, 3.0, true);
   rt.cleanup();
   bc.cleanup();
 }