Add test to improve code coverage

Author: fwesselm

check/TestPresolve.cpp

@@ -838,3 +838,27 @@ TEST_CASE("presolve-egout-ac", "[highs_test_presolve]") {
 
   h.resetGlobalScheduler(true);
 }
+
+TEST_CASE("dual-bound-tightening", "[highs_test_presolve]") {
+  std::string model_file =
+      std::string(HIGHS_DIR) + "/check/instances/gesa2.mps";
+
+  Highs highs;
+  highs.setOptionValue("output_flag", dev_run);
+  highs.readModel(model_file);
+
+  // complement variables to get code coverage
+  HighsLp lp = highs.getLp();
+  std::transform(lp.a_matrix_.value_.begin(), lp.a_matrix_.value_.end(),
+                 lp.a_matrix_.value_.begin(), [](double v) { return -v; });
+  std::transform(lp.col_cost_.begin(), lp.col_cost_.end(), lp.col_cost_.begin(),
+                 [](double v) { return -v; });
+  std::transform(lp.col_upper_.begin(), lp.col_upper_.end(),
+                 lp.col_upper_.begin(), [](double v) { return -v; });
+  std::transform(lp.col_lower_.begin(), lp.col_lower_.end(),
+                 lp.col_lower_.begin(), [](double v) { return -v; });
+  std::swap(lp.col_lower_, lp.col_upper_);
+
+  highs.passModel(lp);
+  REQUIRE(highs.presolve() == HighsStatus::kOk);
+}