testsuite: Test Correlator checkpointing

testsuite/python/save_checkpoint.py

@@ -109,17 +109,22 @@
     system.actors.add(p3m)
 
 obs = espressomd.observables.ParticlePositions(ids=[0, 1])
-acc = espressomd.accumulators.MeanVarianceCalculator(obs=obs)
+acc_mean_variance = espressomd.accumulators.MeanVarianceCalculator(obs=obs)
 acc_time_series = espressomd.accumulators.TimeSeries(obs=obs)
-acc.update()
+acc_correlator = espressomd.accumulators.Correlator(
+    obs1=obs, tau_lin=10, tau_max=2, delta_N=1,
+    corr_operation="componentwise_product")
+acc_mean_variance.update()
 acc_time_series.update()
+acc_correlator.update()
 system.part[0].pos = [1.0, 2.0, 3.0]
-acc.update()
+acc_mean_variance.update()
 acc_time_series.update()
+acc_correlator.update()
 
-
-system.auto_update_accumulators.add(acc)
+system.auto_update_accumulators.add(acc_mean_variance)
 system.auto_update_accumulators.add(acc_time_series)
+system.auto_update_accumulators.add(acc_correlator)
 
 # constraints
 system.constraints.add(shape=Sphere(center=system.box_l / 2, radius=0.1),
@@ -203,8 +208,9 @@
     system.bonded_inter.add(thermalized_bond)
     system.part[1].add_bond((thermalized_bond, 0))
 checkpoint.register("system")
-checkpoint.register("acc")
+checkpoint.register("acc_mean_variance")
 checkpoint.register("acc_time_series")
+checkpoint.register("acc_correlator")
 # calculate forces
 system.integrator.run(0)
 particle_force0 = np.copy(system.part[0].f)

testsuite/python/test_checkpoint.py

@@ -311,9 +311,11 @@ def test_virtual_sites(self):
 
     def test_mean_variance_calculator(self):
         np.testing.assert_array_equal(
-            acc.get_mean(), np.array([[1.0, 1.5, 2.0], [1.0, 1.0, 2.0]]))
+            acc_mean_variance.get_mean(),
+            np.array([[1.0, 1.5, 2.0], [1.0, 1.0, 2.0]]))
         np.testing.assert_array_equal(
-            acc.get_variance(), np.array([[0., 0.5, 2.], [0., 0., 0.]]))
+            acc_mean_variance.get_variance(),
+            np.array([[0., 0.5, 2.], [0., 0., 0.]]))
         np.testing.assert_array_equal(
             system.auto_update_accumulators[0].get_variance(),
             np.array([[0., 0.5, 2.], [0., 0., 0.]]))
@@ -325,6 +327,14 @@ def test_time_series(self):
             system.auto_update_accumulators[1].time_series(),
             expected)
 
+    def test_correlator(self):
+        expected = np.zeros((36, 2, 3))
+        expected[0:2] = [[[1, 2.5, 5], [1, 1, 4]], [[1, 2, 3], [1, 1, 4]]]
+        np.testing.assert_array_equal(acc_correlator.result(), expected)
+        np.testing.assert_array_equal(
+            system.auto_update_accumulators[2].result(),
+            expected)
+
     @utx.skipIfMissingFeatures('P3M')
     @ut.skipIf('P3M.CPU' not in modes,
                "Skipping test due to missing combination.")