Add more unit tests. Refs #6746.

Code/Mantid/Framework/Kernel/src/Statistics.cpp

@@ -229,9 +229,15 @@ namespace Mantid
       if (obsI.size() != calI.size() || obsI.size() != obsE.size())
       {
         std::stringstream errss;
-        errss << "GetRFactor() Input Error!  Observed Intensity, Calculated Intensity and Observed Error have different number of elements.";
+        errss << "GetRFactor() Input Error!  Observed Intensity (" << obsI.size()
+              << "), Calculated Intensity (" << calI.size() << ") and Observed Error ("
+              << obsE.size() << ") have different number of elements.";
         throw std::runtime_error(errss.str());
       }
+      if (obsI.size() == 0)
+      {
+        throw std::runtime_error("getRFactor(): the input arrays are empty.");
+      }
 
       double sumnom = 0;
       double sumdenom = 0;

Code/Mantid/Framework/Kernel/test/StatisticsTest.h

@@ -143,8 +143,45 @@ public:
     double rwp = getRFactor(obsY, calY, obsE);
 
     TS_ASSERT_DELTA(rwp, 0.1582, 0.0001);
+  }
+
+  /** Test throw exception
+    */
+  void testRwpException1()
+  {
+    vector<double> obsY(4);
+    vector<double> calY(4);
+    vector<double> obsE(3);
+
+    obsY[0] = 1.0;
+    calY[0] = 1.1;
+    obsE[0] = 1.0;
+
+    obsY[1] = 2.0;
+    calY[1] = 2.1;
+    obsE[1] = 1.2;
 
+    obsY[2] = 3.0;
+    calY[2] = 3.5;
+    obsE[2] = 1.4;
+
+    obsY[3] = 1.0;
+    calY[3] = 1.3;
+
+    TS_ASSERT_THROWS_ANYTHING(getRFactor(obsY, calY, obsE));
   }
+
+  /** Test throw exception on empty array
+    */
+  void testRwpException2()
+  {
+    vector<double> obsY;
+    vector<double> calY;
+    vector<double> obsE;
+
+    TS_ASSERT_THROWS_ANYTHING(getRFactor(obsY, calY, obsE));
+  }
+
 };
 
 #endif // STATISTICSTEST_H_