fix test

Author: RobbieKiwi

linopy/model.py

@@ -110,7 +110,7 @@ def wrapper(*args: P.args, **kwargs: P.kwargs) -> R:
         # The objective contains a constant term
         if not model.allow_constant_objective:
             raise ConstantObjectiveError(
-                "Objective function contains constant terms. Please use LinearExpression.drop_constants()/QuadraticExpression.drop_constants() or set Model.allow_constant_objective=True."
+                "Objective function contains constant terms. Please use expr.drop_constants() or set model.allow_constant_objective=True."
             )
 
         # Modify the model objective to drop the constant term
@@ -808,7 +808,7 @@ def add_objective(
         | Sequence[tuple[ConstantLike, VariableLike]],
         overwrite: bool = False,
         sense: str = "min",
-        allow_constant: bool | None = None,
+        allow_constant_objective: bool | None = None,
     ) -> None:
         """
         Add an objective function to the model.
@@ -819,7 +819,7 @@ def add_objective(
             Expression describing the objective function.
         overwrite : False, optional
             Whether to overwrite the existing objective. The default is False.
-        allow_constant : bool, optional
+        allow_constant_objective : bool, optional
             Set the `Model.allow_constant_objective` attribute. If True, the objective is allowed to contain a constant term.
 
         Returns
@@ -837,12 +837,12 @@ def add_objective(
 
         self.objective.expression = expr
         self.objective.sense = sense
-        if allow_constant is not None:
-            self.allow_constant_objective = allow_constant
+        if allow_constant_objective is not None:
+            self.allow_constant_objective = allow_constant_objective
 
         if not self.allow_constant_objective and self.objective.has_constant:
             raise ConstantObjectiveError(
-                "Objective function contains constant terms but this is not allowed as Model.allow_constant_objective=False, running solve will result in an error. Please either remove constants from the expression with expr.drop_constants() or set Model.allow_constant_objective=True.",
+                "Objective function contains constant terms but this is not allowed as Model.allow_constant_objective=False. Either remove constants from the expression with expr.drop_constants() or pass allow_constant_objective=True.",
             )
 
     def remove_variables(self, name: str) -> None:

test/test_optimization.py

@@ -948,7 +948,7 @@ def test_model_resolve(
     # add another constraint after solve
     model.add_constraints(model.variables.y >= 3)
 
-    status, condition = model.solve(
+    status, _ = model.solve(
         solver, io_api=io_api, explicit_coordinate_names=explicit_coordinate_names
     )
     assert status == "ok"
@@ -958,7 +958,14 @@ def test_model_resolve(
 
 def test_model_with_constant_in_objective_feasible(model: Model) -> None:
     objective = model.objective.expression + 1
-    model.add_objective(expr=objective, overwrite=True)
+
+    with pytest.raises(ConstantObjectiveError):
+        model.add_objective(
+            expr=objective, overwrite=True, allow_constant_objective=False
+        )
+
+    model.add_objective(expr=objective, overwrite=True, allow_constant_objective=True)
+    model.allow_constant_objective = False
 
     with pytest.raises(ConstantObjectiveError):
         status, _ = model.solve(solver_name="highs")
@@ -974,11 +981,11 @@ def test_model_with_constant_in_objective_feasible(model: Model) -> None:
 
 def test_model_with_constant_in_objective_infeasible(model: Model) -> None:
     objective = model.objective.expression + 1
-    model.add_objective(expr=objective, overwrite=True)
+    model.add_objective(expr=objective, overwrite=True, allow_constant_objective=True)
     model.add_constraints([(1, "x")], "<=", 0)
     model.add_constraints([(1, "y")], "<=", 0)
 
-    _, condition = model.solve(solver_name="highs", allow_constant=True)
+    _, condition = model.solve(solver_name="highs")
 
     assert condition == "infeasible"
     # Even though the problem was not solved, the constant term should still be accessible
@@ -987,7 +994,7 @@ def test_model_with_constant_in_objective_infeasible(model: Model) -> None:
 
 def test_model_with_constant_in_objective_error(model: Model) -> None:
     objective = model.objective.expression + 1
-    model.add_objective(expr=objective, overwrite=True, allow_constant=True)
+    model.add_objective(expr=objective, overwrite=True, allow_constant_objective=True)
     model.add_constraints([(1, "x")], "<=", 0)
     model.add_constraints([(1, "y")], "<=", 0)