Updated test_parmest.py

Author: slilonfe5

pyomo/contrib/parmest/parmest.py

@@ -1700,7 +1700,11 @@ def _cov_at_theta(self, method, solver, step):
 
                 # fix the value of the unknown parameters to the estimated values
                 for param in model.unknown_parameters:
-                    param.fix(self.estimated_theta[param.name])
+                    if param.is_indexed():
+                        for idx in param:
+                            param[idx].fix(self.estimated_theta[param[idx].name])
+                    else:
+                        param.fix(self.estimated_theta[param.name])
 
                 # re-solve the model with the estimated parameters
                 results = pyo.SolverFactory(solver).solve(model, tee=self.tee)

pyomo/contrib/parmest/tests/test_parmest.py

@@ -2275,6 +2275,8 @@ def test_indexed_unknown_parameter_names_are_expanded_consistently(self):
     def test_cov_est_counts_expanded_indexed_unknown_parameters(self):
         pest = _build_indexed_theta_estimator([(1.0, 2.0), (2.0, 4.0)])
 
+        obj, theta = pest.theta_est()
+
         with self.assertRaisesRegex(
             AssertionError,
             "The number of datapoints must be greater than the number of parameters to estimate.",