Added maximization test to dual objective value unit test

check/TestLpSolvers.cpp

@@ -2,7 +2,7 @@
 #include "Highs.h"
 #include "catch.hpp"
 
-const bool dev_run = true;  // false;
+const bool dev_run = false;
 
 struct IterationCount {
   HighsInt simplex;
@@ -491,6 +491,34 @@ TEST_CASE("blending-lp-ipm", "[highs_lp_solver]") {
   REQUIRE(highs.getModelStatus() == HighsModelStatus::kOptimal);
 }
 
+TEST_CASE("dual-objective-max", "[highs_lp_solver]") {
+  Highs highs;
+  highs.setOptionValue("output_flag", dev_run);
+  HighsLp lp;
+  lp.num_col_ = 2;
+  lp.num_row_ = 2;
+  lp.sense_ = ObjSense::kMaximize;
+  lp.offset_ = 10;
+  lp.col_cost_ = {8, 10};
+  lp.col_lower_ = {0, 0};
+  lp.col_upper_ = {kHighsInf, kHighsInf};
+  lp.row_lower_ = {-kHighsInf, -kHighsInf};
+  lp.row_upper_ = {80, 120};
+  lp.a_matrix_.start_ = {0, 2, 4};
+  lp.a_matrix_.index_ = {0, 1, 0, 1};
+  lp.a_matrix_.value_ = {1, 1, 2, 4};
+  highs.passModel(lp);
+  highs.run();
+  double dual_objective;
+  HighsStatus return_status = highs.getDualObjectiveValue(dual_objective);
+  REQUIRE(return_status == HighsStatus::kOk);
+  double primal_objective = highs.getInfo().objective_function_value;
+  double relative_primal_dual_gap =
+      std::fabs(primal_objective - dual_objective) /
+      std::max(1.0, std::fabs(primal_objective));
+  REQUIRE(relative_primal_dual_gap < 1e-12);
+}
+
 TEST_CASE("dual-objective", "[highs_lp_solver]") {
   testDualObjective("avgas");
   testDualObjective("adlittle");