fixing segfaults occuring when launching those unit tests

modules/calib3d/test/test_cameracalibration.cpp

@@ -1570,7 +1570,8 @@ void CV_StereoCalibrationTest::run( int )
         {
             ts->printf( cvtest::TS::LOG, "The file %s can not be opened or has invalid content\n", filepath.c_str() );
             ts->set_failed_test_info( f ? cvtest::TS::FAIL_INVALID_TEST_DATA : cvtest::TS::FAIL_MISSING_TEST_DATA );
-            fclose(f);
+            if (f)
+                fclose(f);
             return;
         }
 

modules/ml/src/lr.cpp

@@ -138,6 +138,9 @@ bool LogisticRegressionImpl::train(const Ptr<TrainData>& trainData, int)
     // return value
     bool ok = false;
 
+    if (trainData.empty()) {
+        return false;
+    }
     clear();
     Mat _data_i = trainData->getSamples();
     Mat _labels_i = trainData->getResponses();

modules/ml/test/test_emknearestkmeans.cpp

@@ -618,6 +618,7 @@ protected:
         {
             ts->printf(cvtest::TS::LOG, "File with spambase dataset cann't be read.\n");
             ts->set_failed_test_info(cvtest::TS::FAIL_INVALID_TEST_DATA);
+            return;
         }
 
         Mat samples = data->getSamples();

modules/ml/test/test_lr.cpp

@@ -95,6 +95,11 @@ void CV_LRTest::run( int /*start_from*/ )
     string dataFileName = ts->get_data_path() + "iris.data";
     Ptr<TrainData> tdata = TrainData::loadFromCSV(dataFileName, 0);
 
+    if (tdata.empty()) {
+        ts->set_failed_test_info(cvtest::TS::FAIL_INVALID_TEST_DATA);
+        return;
+    }
+
     // run LR classifier train classifier
     Ptr<LogisticRegression> p = LogisticRegression::create();
     p->setLearningRate(1.0);

modules/shape/test/test_shape.cpp

@@ -83,6 +83,9 @@ protected:
 
     vector<PointType> convertContourType(const Mat& currentQuery) const
     {
+        if (currentQuery.empty()) {
+            return vector<PointType>();
+        }
         vector<vector<Point> > _contoursQuery;
         findContours(currentQuery, _contoursQuery, RETR_LIST, CHAIN_APPROX_NONE);