refactor: remove references to backend from freezing dynamic and move…

… freezing unit test to tests/unit_tests/dynamics. closes #1154 (#1515)

PySDM/dynamics/freezing.py

@@ -2,10 +2,6 @@
 immersion freezing using either singular or time-dependent formulation
 """
 
-from PySDM.backends.impl_common.freezing_attributes import (
-    SingularAttributes,
-    TimeDependentAttributes,
-)
 from PySDM.physics.heterogeneous_ice_nucleation_rate import Null
 from PySDM.dynamics.impl import register_dynamic
 
@@ -25,22 +21,24 @@ def __init__(self, *, singular=True, record_freezing_temperature=False, thaw=Fal
     def register(self, builder):
         self.particulator = builder.particulator
 
-        assert builder.formulae.particle_shape_and_density.supports_mixed_phase()
+        assert (
+            self.particulator.formulae.particle_shape_and_density.supports_mixed_phase()
+        )
 
         builder.request_attribute("signed water mass")
         if self.singular or self.record_freezing_temperature:
             builder.request_attribute("freezing temperature")
 
         if not self.singular:
             assert not isinstance(
-                builder.formulae.heterogeneous_ice_nucleation_rate, Null
+                self.particulator.formulae.heterogeneous_ice_nucleation_rate, Null
             )
             builder.request_attribute("immersed surface area")
             self.rand = self.particulator.Storage.empty(
                 self.particulator.n_sd, dtype=float
             )
             self.rng = self.particulator.Random(
-                self.particulator.n_sd, self.particulator.backend.formulae.seed
+                self.particulator.n_sd, self.particulator.formulae.seed
             )
 
     def __call__(self):
@@ -54,39 +52,12 @@ def __call__(self):
             return
 
         if self.singular:
-            self.particulator.backend.freeze_singular(
-                attributes=SingularAttributes(
-                    freezing_temperature=self.particulator.attributes[
-                        "freezing temperature"
-                    ],
-                    signed_water_mass=self.particulator.attributes["signed water mass"],
-                ),
-                temperature=self.particulator.environment["T"],
-                relative_humidity=self.particulator.environment["RH"],
-                cell=self.particulator.attributes["cell id"],
-                thaw=self.thaw,
-            )
+            self.particulator.immersion_freezing_singular(thaw=self.thaw)
         else:
             self.rand.urand(self.rng)
-            self.particulator.backend.freeze_time_dependent(
+            self.particulator.immersion_freezing_time_dependent(
                 rand=self.rand,
-                attributes=TimeDependentAttributes(
-                    immersed_surface_area=self.particulator.attributes[
-                        "immersed surface area"
-                    ],
-                    signed_water_mass=self.particulator.attributes["signed water mass"],
-                ),
-                timestep=self.particulator.dt,
-                cell=self.particulator.attributes["cell id"],
-                a_w_ice=self.particulator.environment["a_w_ice"],
-                temperature=self.particulator.environment["T"],
-                relative_humidity=self.particulator.environment["RH"],
                 record_freezing_temperature=self.record_freezing_temperature,
-                freezing_temperature=(
-                    self.particulator.attributes["freezing temperature"]
-                    if self.record_freezing_temperature
-                    else None
-                ),
                 thaw=self.thaw,
             )
 

PySDM/particulator.py

@@ -5,6 +5,10 @@
 import numpy as np
 
 from PySDM.backends.impl_common.backend_methods import BackendMethods
+from PySDM.backends.impl_common.freezing_attributes import (
+    SingularAttributes,
+    TimeDependentAttributes,
+)
 from PySDM.backends.impl_common.index import make_Index
 from PySDM.backends.impl_common.indexed_storage import make_IndexedStorage
 from PySDM.backends.impl_common.pair_indicator import make_PairIndicator
@@ -479,3 +483,38 @@ def seeding(
         self.attributes.mark_updated("multiplicity")
         for key in self.attributes.get_extensive_attribute_keys():
             self.attributes.mark_updated(key)
+
+    def immersion_freezing_time_dependent(
+        self, *, thaw: bool, record_freezing_temperature: bool, rand: Storage
+    ):
+        self.backend.freeze_time_dependent(
+            rand=rand,
+            attributes=TimeDependentAttributes(
+                immersed_surface_area=self.attributes["immersed surface area"],
+                signed_water_mass=self.attributes["signed water mass"],
+            ),
+            timestep=self.dt,
+            cell=self.attributes["cell id"],
+            a_w_ice=self.environment["a_w_ice"],
+            temperature=self.environment["T"],
+            relative_humidity=self.environment["RH"],
+            record_freezing_temperature=record_freezing_temperature,
+            freezing_temperature=(
+                self.attributes["freezing temperature"]
+                if record_freezing_temperature
+                else None
+            ),
+            thaw=thaw,
+        )
+
+    def immersion_freezing_singular(self, *, thaw: bool):
+        self.backend.freeze_singular(
+            attributes=SingularAttributes(
+                freezing_temperature=self.attributes["freezing temperature"],
+                signed_water_mass=self.attributes["signed water mass"],
+            ),
+            temperature=self.environment["T"],
+            relative_humidity=self.environment["RH"],
+            cell=self.attributes["cell id"],
+            thaw=thaw,
+        )

tests/unit_tests/backends/test_freezing_methods.py → tests/unit_tests/dynamics/test_immersion_freezing.py

@@ -10,7 +10,7 @@
 from PySDM.products import IceWaterContent
 
 
-class TestFreezingMethods:
+class TestImmersionFreezing:
     # TODO #599
     def test_record_freezing_temperature_on_time_dependent_freeze(self):
         pass