Fix incorrect calculation of max in QgsStatisticalSummary

Author: nyalldawson

src/core/qgsstatisticalsummary.cpp

@@ -36,7 +36,7 @@ void QgsStatisticalSummary::reset()
   mMean = 0;
   mMedian = 0;
   mMin = std::numeric_limits<double>::max();
-  mMax = std::numeric_limits<double>::min();
+  mMax = -std::numeric_limits<double>::max();
   mStdev = 0;
   mSampleStdev = 0;
   mMinority = 0;

tests/src/core/testqgsstatisticalsummary.cpp

@@ -32,6 +32,7 @@ class TestQgsStatisticSummary: public QObject
     void init();// will be called before each testfunction is executed.
     void cleanup();// will be called after every testfunction.
     void stats();
+    void maxMin();
 
   private:
 
@@ -119,5 +120,18 @@ void TestQgsStatisticSummary::stats()
   QCOMPARE( s.interQuartileRange(), 11.0 );
 }
 
+void TestQgsStatisticSummary::maxMin()
+{
+  QgsStatisticalSummary s( QgsStatisticalSummary::All );
+
+  //test max/min of negative value list
+  QList<double> negativeVals;
+  negativeVals << -5.0 << -10.0 << -15.0;
+  s.calculate( negativeVals );
+
+  QCOMPARE( s.min(), -15.0 );
+  QCOMPARE( s.max(), -5.0 );
+}
+
 QTEST_MAIN( TestQgsStatisticSummary )
 #include "testqgsstatisticalsummary.moc"