Fixed test failure in TestIis.cpp

Author: hbagheri

check/TestIis.cpp

@@ -461,9 +461,9 @@ TEST_CASE("lp-get-iis-galenet", "[iis]") {
 
 TEST_CASE("lp-get-iis-avgas", "[iis]") {
   std::string model = "avgas";
-  // For the whole LP calculation the elasticity filter only
-  // identified feasibility, so the model status is not set
-  testMps(model, kIisStrategyFromLp, HighsModelStatus::kNotset);
+  // For the whole LP calculation feasibility is established prior to elasticity
+  // filter so the model status will be optimal
+  testMps(model, kIisStrategyFromLp, HighsModelStatus::kOptimal);
   // For the ray calculation the model is solved, so its status is
   // known
   //  testMps(model, kIisStrategyFromRay,

highs/lp_data/HighsInterface.cpp

@@ -1935,6 +1935,8 @@ HighsStatus Highs::getIisInterface() {
   // light strategy
   if (options_.iis_strategy == kIisStrategyLight)
     return this->getIisInterfaceReturn(HighsStatus::kOk, options_, callback_);
+  // Clear IIS
+  this->iis_.clear();
   // Save original options and callback
   HighsOptions original_options = this->options_;
   HighsCallback original_callback = this->callback_;
@@ -1994,11 +1996,9 @@ HighsStatus Highs::getIisInterface() {
 
   // Construct an IS from ray or lp
   bool ray_option =
-      // (kIisStrategyFromRay & options_.iis_strategy) ||
-      // (kIisStrategyIrreducible & options_.iis_strategy)
+      // kIisStrategyFromRay & options_.iis_strategy;
       false;
-  const bool lp_option = (kIisStrategyFromLp & options_.iis_strategy) ||
-                         (kIisStrategyIrreducible & options_.iis_strategy);
+  const bool lp_option = kIisStrategyFromLp & options_.iis_strategy;
   if (ray_option && !ekk_instance_.status_.has_invert) {
     // Model is known to be infeasible, and a dual ray option is
     // chosen, but it has no INVERT, presumably because infeasibility
@@ -2074,8 +2074,8 @@ HighsStatus Highs::getIisInterface() {
     return this->getIisInterfaceReturn(return_status, original_options,
                                        original_callback);
 
-  // If both ray and lp options fail to produce a valid IS, make one consisting
-  // of all constraints
+  // If neither ray and lp options were requested or if they fail to produce a
+  // valid IS, make one consisting of all constraints
   if (!this->iis_.valid_) {
     this->iis_.valid_ = true;
     this->iis_.status_ = kIisModelStatusReducible;