[HOLD] Track variational solver convergence

tests/shard4/test_variational_integrator_examples.py

@@ -30,6 +30,7 @@ def test_variational_pendulum(use_sx):
 
     # --- Solve the ocp --- #
     sol = ocp.solve(Solver.IPOPT())
+    TestUtils.assert_solver_success(sol, max_iterations=100)
     states = sol.decision_states(to_merge=SolutionMerge.NODES)
     controls = sol.decision_controls(to_merge=SolutionMerge.NODES)
 
@@ -64,6 +65,7 @@ def test_variational_pendulum_with_holonomic_constraints(use_sx):
 
     # --- Solve the ocp --- #
     sol = ocp.solve(Solver.IPOPT())
+    TestUtils.assert_solver_success(sol, max_iterations=100)
     states = sol.decision_states(to_merge=SolutionMerge.NODES)
     controls = sol.decision_controls(to_merge=SolutionMerge.NODES)
 

tests/utils.py

@@ -30,6 +30,18 @@
 
 
 class TestUtils:
+    @staticmethod
+    def assert_solver_success(solution: Solution, max_iterations: int | None = None):
+        """Assert convergence and optionally guard against a large iteration-count regression."""
+        assert solution.status == 0, (
+            f"Solver did not converge (status={solution.status}, iterations={solution.iterations})"
+        )
+        assert isinstance(solution.iterations, int) and solution.iterations >= 0
+        if max_iterations is not None:
+            assert solution.iterations <= max_iterations, (
+                f"Solver iteration regression: {solution.iterations} iterations, expected at most {max_iterations}"
+            )
+
     @staticmethod
     def bioptim_folder() -> str:
         return TestUtils._capitalize_folder_drive(str(Path(__file__).parent / "../bioptim"))