Rationalised/extended testing for #2409; updated FEATURES.md; formatted

Author: jajhall

FEATURES.md

@@ -2,5 +2,7 @@
 
 ## Code changes
 
+Forcing column reduction now checks the bound on the column dual rather than whether the dual row activity is zero fixing [#2409](https://github.com/ERGO-Code/HiGHS/issues/2409)
+
 
 

check/TestMipSolver.cpp

@@ -946,9 +946,22 @@ TEST_CASE("issue-2409", "[highs_test_mip_solver]") {
   lp.a_matrix_.value_ = {-1, 1, 1, 1};
   lp.integrality_ = {HighsVarType::kContinuous, HighsVarType::kInteger};
   require_model_status = HighsModelStatus::kOptimal;
-  optimal_objective = 0.9;
+  optimal_objective = 0.1;
   Highs highs;
   REQUIRE(highs.passModel(lp) == HighsStatus::kOk);
-  //  solve(highs, kHighsOnString, require_model_status, optimal_objective);
+  if (dev_run) printf("Testing that presolve reduces the problem to empty\n");
+  REQUIRE(highs.presolve() == HighsStatus::kOk);
+  REQUIRE(highs.getModelPresolveStatus() ==
+          HighsPresolveStatus::kReducedToEmpty);
+
+  if (dev_run)
+    printf(
+        "\nTesting that with presolve the correct optimal objecive is found\n");
+  solve(highs, kHighsOnString, require_model_status, optimal_objective);
+  highs.clearSolver();
+  if (dev_run)
+    printf(
+        "\nTesting that without presolve the correct optimal objecive is "
+        "found\n");
   solve(highs, kHighsOffString, require_model_status, optimal_objective);
 }

check/TestPresolve.cpp

@@ -724,14 +724,3 @@ TEST_CASE("presolve-issue-2402", "[highs_test_presolve]") {
   REQUIRE(highs.presolve() == HighsStatus::kOk);
   REQUIRE(highs.getModelPresolveStatus() == HighsPresolveStatus::kInfeasible);
 }
-
-TEST_CASE("presolve-issue-2409", "[highs_test_presolve]") {
-  std::string model_file =
-      std::string(HIGHS_DIR) + "/check/instances/issue-2409.mps";
-  Highs highs;
-  highs.setOptionValue("output_flag", dev_run);
-  highs.readModel(model_file);
-  REQUIRE(highs.presolve() == HighsStatus::kOk);
-  REQUIRE(highs.getModelPresolveStatus() ==
-          HighsPresolveStatus::kReducedToEmpty);
-}