Add jet, surface and fixed-patch tests and runnable examples

tests/integration/test_body_sync_e2e.py

@@ -7,9 +7,9 @@ import unittest
 import tempfile
 
 import numpy as np
-import pycuda.autoinit
 
 from CelerisLab.simulation import Simulation
+from ._cases import make_sim
 from CelerisLab.lbm.descriptors import OBSTACLE, FLUID
 
 
@@ -18,7 +18,7 @@ class TestBodySyncE2E(unittest.TestCase):
 
     def test_full_lifecycle(self):
         """Create, init, run, add body, remove body, checkpoint, load."""
-        sim = Simulation(device_id=0)
+        sim = make_sim()
         nx = sim.lbm_cfg.nx
         ny = sim.lbm_cfg.ny
         cx, cy = nx // 4, ny // 2
@@ -61,7 +61,7 @@ class TestBodySyncE2E(unittest.TestCase):
             self.assertTrue(os.path.exists(saved_path))
 
             # 7. Load checkpoint in a new simulation
-            sim2 = Simulation(device_id=0)
+            sim2 = make_sim()
             sim2.initialize()
             sim2.run(1)
 
@@ -71,9 +71,10 @@ class TestBodySyncE2E(unittest.TestCase):
 
             # 8. Continue running in restored sim
             sim2.run(50)
-            # Verify step count advances (DDF may have NaN from pre-existing body)
+            # Verify the restored field remains finite and stepping advances
             self.assertEqual(sim2.stepper.step_count,
                              sim.stepper.step_count + 50)
+            self.assertTrue(np.all(np.isfinite(sim2.get_ddf())))
             sim2.close()
         finally:
             os.unlink(ckpt_path)
@@ -82,7 +83,7 @@ class TestBodySyncE2E(unittest.TestCase):
 
     def test_add_remove_add_cycle(self):
         """Add → run → remove → run → add → run cycle with finite checks."""
-        sim = Simulation(device_id=0)
+        sim = make_sim()
         nx = sim.lbm_cfg.nx
         ny = sim.lbm_cfg.ny
         cx, cy = nx // 4, ny // 2