Remove incorrect getter for DualObjectiveValue (#207)

Author: odow

src/AmplNLWriter.jl

@@ -352,10 +352,4 @@ function MOI.get(
     return MOI.get(model.results, attr, ci)
 end
 
-function MOI.get(model::Optimizer, attr::MOI.DualObjectiveValue)
-    MOI.check_result_index_bounds(model, attr)
-    # TODO(odow): replace this with the proper dual objective.
-    return MOI.get(model, MOI.ObjectiveValue())
-end
-
-end
+end  # module

test/MOI_wrapper.jl

@@ -55,6 +55,7 @@ function test_ipopt_runtests()
                 MOI.VariableBasisStatus,
                 MOI.ConstraintBasisStatus,
                 MOI.ObjectiveBound,
+                MOI.DualObjectiveValue,
             ],
         ),
         exclude = [