Add a unit test for edge3 side vertex average

Author: GiudGiud

tests/geom/side_vertex_average_normal_test.C

@@ -79,6 +79,37 @@ public:
     }
   }
 
+  void testEdge3()
+  {
+    LOG_UNIT_TEST;
+
+    {
+      // Reference
+      const Elem & edge3 = ReferenceElem::get(EDGE3);
+      const Point n1 = edge3.side_vertex_average_normal(0);
+      LIBMESH_ASSERT_FP_EQUAL(-1, n1(0), TOLERANCE*TOLERANCE);
+      LIBMESH_ASSERT_FP_EQUAL(0, n1(1), TOLERANCE*TOLERANCE);
+      LIBMESH_ASSERT_FP_EQUAL(0, n1(2), TOLERANCE*TOLERANCE);
+      const Point n2 = edge3.side_vertex_average_normal(1);
+      LIBMESH_ASSERT_FP_EQUAL(1, n2(0), TOLERANCE*TOLERANCE);
+      LIBMESH_ASSERT_FP_EQUAL(0, n2(1), TOLERANCE*TOLERANCE);
+      LIBMESH_ASSERT_FP_EQUAL(0, n2(2), TOLERANCE*TOLERANCE);
+    }
+    {
+      // Oriented
+      std::vector<Point> pts = {Point(1, 0, 0), Point(1, 3, 0), Point(2, 1, 0)};
+      auto [edge3, nodes] = this->construct_elem(pts, EDGE3);
+      const Point n1 = edge3->side_vertex_average_normal(0);
+      LIBMESH_ASSERT_FP_EQUAL(-sqrt(2) / 2, n1(0), TOLERANCE*TOLERANCE);
+      LIBMESH_ASSERT_FP_EQUAL(-sqrt(2) / 2, n1(1), TOLERANCE*TOLERANCE);
+      LIBMESH_ASSERT_FP_EQUAL(0, n1(2), TOLERANCE*TOLERANCE);
+      const Point n2 = edge3->side_vertex_average_normal(1);
+      LIBMESH_ASSERT_FP_EQUAL(sqrt(3) / 2, n2(0), TOLERANCE*TOLERANCE);
+      LIBMESH_ASSERT_FP_EQUAL(1. / 2, n2(1), TOLERANCE*TOLERANCE);
+      LIBMESH_ASSERT_FP_EQUAL(0, n2(2), TOLERANCE*TOLERANCE);
+    }
+  }
+
   void testTri3()
   {
     LOG_UNIT_TEST;