Add test and fix bug

Author: pipliggins

src/pybamm/solvers/base_solver.py

@@ -789,7 +789,7 @@ def solve(
                         for it in model.concatenated_initial_conditions.pre_order()
                     ]
                 )
-                if all_inputs_names.issubset(initial_conditions_node_names):
+                if not initial_conditions_node_names.isdisjoint(all_inputs_names):
                     raise pybamm.SolverError(
                         "Input parameters cannot appear in expression "
                         "for initial conditions."
@@ -839,9 +839,9 @@ def solve(
                 # If the new initial conditions are different
                 # and cannot be evaluated directly, set up again
                 self.set_up(model, model_inputs_list[0], t_eval, ics_only=True)
-            self._model_set_up[model]["initial conditions"] = (
-                model.concatenated_initial_conditions
-            )
+            self._model_set_up[model][
+                "initial conditions"
+            ] = model.concatenated_initial_conditions
         else:
             # Set the standard initial conditions
             self._set_initial_conditions(model, t_eval[0], model_inputs_list[0])

tests/unit/test_solvers/test_base_solver.py

@@ -446,3 +446,33 @@ def test_on_extrapolation_and_on_failure_settings(self):
             ValueError, match="on_failure must be 'warn', 'raise', or 'ignore'"
         ):
             base_solver.on_failure = "invalid"
+
+    def test_solver_multiple_inputs_initial_conditions_error(self):
+
+        y = pybamm.Variable("y")
+        y0 = pybamm.InputParameter("y0")
+        k = pybamm.InputParameter("k")
+
+        model = pybamm.BaseModel()
+        model.rhs = {y: -k * y}
+        model.initial_conditions = {y: y0}
+        model.variables = {"y": y}
+
+        disc = pybamm.Discretisation()
+        disc.process_model(model)
+
+        t_eval = np.linspace(0.0, 1.0, 6)
+
+        # Three different ICs so each run is clearly distinct
+        inputs_list = [
+            {"y0": 1.0, "k": 0.5},
+            {"y0": 2.0, "k": 1.0},
+            {"y0": 3.0, "k": 1.5},
+        ]
+
+        solver = pybamm.BaseSolver()
+        with pytest.raises(
+            pybamm.SolverError,
+            match="Input parameters cannot appear in expression for initial conditions",
+        ):
+            solver.solve(model, t_eval=t_eval, inputs=inputs_list)