Make t and n optional arguments in store_checkpoint (#178)

* Make t and n optional arguments in store_checkpoint
* Add integration tests

Author: NiklasVin

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## develop
 
 * Set required version of `scipy` to `<1.15.0` to prevent failing tests because of a required module that is not found for later versions of scipy. [#195](https://github.com/precice/fenics-adapter/pull/195)
+* `store_checkpoint` no longer requires the time `t` and the current time window number `n` as parameters as they are now optional. If they are not specified in `store_checkpoint`, `retrieve_checkpoint` still returns a tuple of three elements but for unspecified parameters, it returns `None`.
 
 ## 2.2.0
 

fenicsprecice/fenicsprecice.py

@@ -432,17 +432,17 @@ def initialize(self, coupling_subdomain, read_function_space=None, write_object=
 
         self._participant.initialize()
 
-    def store_checkpoint(self, payload, t, n):
+    def store_checkpoint(self, payload, t=None, n=None):
         """
         Defines an object of class SolverState which stores the current state of the variable and the time stamp.
 
         Parameters
         ----------
         payload : fenics.function or a list of fenics.functions
             Current state of the physical variable(s) of interest for this participant.
-        t : double
+        t : double (optional)
             Current simulation time.
-        n : int
+        n : int (optional)
             Current time window (iteration) number.
         """
         if self._first_advance_done:
@@ -460,9 +460,9 @@ def retrieve_checkpoint(self):
         u : FEniCS Function
             Current state of the physical variable of interest for this participant.
         t : double
-            Current simulation time.
+            Current simulation time or None if not specified in store_checkpoint
         n : int
-            Current time window (iteration) number.
+            Current time window (iteration) number or None if not specified in store_checkpoint
         """
         assert (not self.is_time_window_complete())
         logger.debug("Restore solver state")

tests/integration/test_write_read.py

@@ -1,7 +1,7 @@
 from unittest.mock import MagicMock, patch
 from unittest import TestCase
 from tests import MockedPrecice
-from fenics import Expression, UnitSquareMesh, FunctionSpace, VectorFunctionSpace, interpolate, SubDomain, near
+from fenics import Expression, UnitSquareMesh, FunctionSpace, VectorFunctionSpace, interpolate, SubDomain, near, UnitIntervalMesh
 import numpy as np
 
 x_left, x_right = 0, 1
@@ -185,3 +185,74 @@ def return_dummy_data(n_points):
                 self.fail(f"Unexpected combination of arg: {arg}, expected_arg: {expected_arg}")
 
         np.testing.assert_almost_equal(list(read_data.values()), return_dummy_data(self.n_vertices))
+
+    def test_optional_parameters(self):
+        from precice import Participant
+        import fenicsprecice
+
+        def test_all_parameters(adapter):
+            # init variables that are tested against
+            nx = 10
+            mesh = UnitIntervalMesh(nx)
+            V = FunctionSpace(mesh, 'P', 2)
+            dummy_value = 1
+            E = Expression("t", t=dummy_value, degree=2)
+            u = interpolate(E, V)
+            t = 0.5
+            n = 42
+            # test adapter
+            adapter.store_checkpoint(u, t, n)  # is the old implementation still working?
+            res_u, res_t, res_n = adapter.retrieve_checkpoint()
+            self.assertEqual(res_t, t)
+            self.assertEqual(res_n, n)
+            np.testing.assert_array_equal(res_u.vector(), u.vector())
+
+        def test_opt_parameters(adapter):
+            # init variables that are tested against
+            nx = 10
+            mesh = UnitIntervalMesh(nx)
+            V = FunctionSpace(mesh, 'P', 2)
+            dummy_value = 1
+            E = Expression("t", t=dummy_value, degree=2)
+            u = interpolate(E, V)
+            t = 0.5
+            n = 42
+            # test adapter
+            adapter.store_checkpoint(u, t=t)  # without n
+            res = adapter.retrieve_checkpoint()
+            self.assertEqual(len(res), 3)  # correct number of return values
+            res_u, res_t, res_n = res
+            self.assertEqual(res_t, t)
+            self.assertEqual(res_n, None)
+            np.testing.assert_array_equal(res_u.vector(), u.vector())
+
+            adapter.store_checkpoint(u, n=n)  # without t
+            res = adapter.retrieve_checkpoint()
+            self.assertEqual(len(res), 3)  # correct number of return values
+            res_u, res_t, res_n = res
+            self.assertEqual(res_n, n)
+            self.assertEqual(res_t, None)
+            np.testing.assert_array_equal(res_u.vector(), u.vector())
+
+        def test_payload_only(adapter):
+            nx = 10
+            mesh = UnitIntervalMesh(nx)
+            V = FunctionSpace(mesh, 'P', 2)
+            dummy_value = 1
+            E = Expression("t", t=dummy_value, degree=2)
+            u = interpolate(E, V)
+            # test adapter
+            adapter.store_checkpoint(u)  # no optional parameters
+            res_u, res_t, res_n = adapter.retrieve_checkpoint()
+            self.assertEqual(res_t, None)
+            self.assertEqual(res_n, None)
+            np.testing.assert_array_equal(res_u.vector(), u.vector())
+
+        Participant.is_time_window_complete = MagicMock(return_value=False)
+
+        precice = fenicsprecice.Adapter(self.dummy_config)
+
+        # call the tests
+        test_all_parameters(precice)
+        test_opt_parameters(precice)
+        test_payload_only(precice)