#963 add more tests

pybamm/discretisations/discretisation.py

@@ -117,6 +117,12 @@ def process_model(self, model, inplace=True, check_model=True):
             `model.variables = {}`)
 
         """
+        if model.is_discretised is True:
+            raise pybamm.ModelError(
+                "Cannot re-discretise a model. "
+                "Set 'inplace=False' when first discretising a model to then be able "
+                "to discretise it more times (e.g. for convergence studies)."
+            )
 
         pybamm.logger.info("Start discretising {}".format(model.name))
 

tests/unit/test_discretisations/test_discretisation.py

@@ -601,9 +601,10 @@ def test_process_model_ode(self):
 
         combined_submesh = mesh.combine_submeshes(*whole_cell)
         disc.process_model(model)
-        # Processing twice should work
-        disc = get_discretisation_for_testing()
-        disc.process_model(model)
+
+        # We cannot re-discretise after discretising a first time
+        with self.assertRaisesRegex(pybamm.ModelError, "Cannot re-discretise a model"):
+            disc.process_model(model)
 
         y0 = model.concatenated_initial_conditions.evaluate()
         np.testing.assert_array_equal(
@@ -765,6 +766,7 @@ def test_process_model_dae(self):
         mesh = disc.mesh
 
         disc.process_model(model)
+
         combined_submesh = mesh.combine_submeshes(*whole_cell)
 
         y0 = model.concatenated_initial_conditions.evaluate()
@@ -1119,7 +1121,7 @@ def test_exceptions(self):
 
         # check doesn't raise if concatenation
         model.variables = {c_n.name: pybamm.Concatenation(c_n, c_s)}
-        disc.process_model(model)
+        disc.process_model(model, inplace=False)
 
         # check doesn't raise if broadcast
         model.variables = {