added: unit tests for gaussian quadrature

src/Utility/Test/TestGaussQuadrature.C

@@ -0,0 +1,45 @@
+//==============================================================================
+//!
+//! \file TestGaussQuadrature.C
+//!
+//! \date Dec 31 2017
+//!
+//! \author Arne Morten Kvarving / SINTEF
+//!
+//! \brief Tests for Gaussian quadratures.
+//!
+//==============================================================================
+
+#include "GaussQuadrature.h"
+
+#include "gtest/gtest.h"
+#include <cmath>
+
+class TestGaussQuadrature : public testing::Test,
+                            public testing::WithParamInterface<int>
+{
+};
+
+
+TEST_P(TestGaussQuadrature, Integrate)
+{
+  const double* xi = GaussQuadrature::getCoord(GetParam());
+  const double* wi = GaussQuadrature::getWeight(GetParam());
+
+  double res = 0.0;
+  for (int i = 0; i < GetParam(); ++i) {
+    for (int p = 0; p < GetParam(); ++p)
+      res += wi[i]*pow(xi[i], p); // 1+x+x^2+x^3+..
+  }
+
+  double exa = 0.0;
+  for (int p = 0; p < GetParam(); ++p)
+    exa += 1.0/(p+1) * (pow(1.0, p+1) - pow(-1.0, p+1));
+
+  EXPECT_FLOAT_EQ(res, exa);
+}
+
+
+INSTANTIATE_TEST_CASE_P(TestGaussQuadrature,
+                        TestGaussQuadrature,
+                        testing::ValuesIn({1, 2, 3, 4, 5, 6, 7, 8, 9, 10}));