[test] add test for 0d-1d intersections

test/common/geometry/CMakeLists.txt

+dune_add_test(SOURCES test_0d1d_intersection.cc LABELS unit)
 dune_add_test(SOURCES test_1d3d_intersection.cc LABELS unit)
 dune_add_test(SOURCES test_1d2d_intersection.cc LABELS unit)
 dune_add_test(SOURCES test_2d3d_intersection.cc LABELS unit)

test/common/geometry/test_0d1d_intersection.cc

+#include <config.h>
+
+#include <iostream>
+#include <algorithm>
+#include <initializer_list>
+
+#include <dune/common/exceptions.hh>
+#include <dune/common/parallel/mpihelper.hh>
+#include <dune/common/fvector.hh>
+
+#include <dumux/common/geometry/intersectspointgeometry.hh>
+
+#ifndef DOXYGEN
+template<int dimworld = 3>
+bool testIntersection(const Dune::FieldVector<double, dimworld>& a,
+                      const Dune::FieldVector<double, dimworld>& b,
+                      const Dune::FieldVector<double, dimworld>& p,
+                      bool foundExpected = false)
+{
+    bool found = Dumux::intersectsPointSimplex(p, a, b);
+    if (!found && foundExpected)
+        std::cerr << "Failed detecting intersection with " << p << std::endl;
+    else if (found && foundExpected)
+        std::cout << "Found intersection with " << p << std::endl;
+    else if (found && !foundExpected)
+        std::cerr << "Found false positive: intersection with " << p << std::endl;
+    else if (!found && !foundExpected)
+        std::cout << "No intersection with " << p << std::endl;
+    return (found == foundExpected);
+}
+
+template<int dimWorld>
+void testIntersections(std::vector<bool>& returns)
+{
+    // test if points lie on 3d segments
+    using GlobalPosition = Dune::FieldVector<double, dimWorld>;
+
+    for (auto scaling : {1.0, 1e3, 1e12, 1e-12})
+    {
+        const GlobalPosition a(0.0);
+        auto b = a;
+        b[dimWorld-1] = 1.0*scaling;
+
+        GlobalPosition p1 = a;
+        GlobalPosition p2 = b;
+        GlobalPosition p3 = a + b;
+        p3 /= 2.0;
+        GlobalPosition p4 = b + (b - a);
+        GlobalPosition p5 = a - (b - a);
+        GlobalPosition p6(0.5*scaling);
+
+        returns.push_back(testIntersection(a, b, p1, true));
+        returns.push_back(testIntersection(a, b, p2, true));
+        returns.push_back(testIntersection(a, b, p3, true));
+        returns.push_back(testIntersection(a, b, p4));
+        returns.push_back(testIntersection(a, b, p5));
+        returns.push_back(testIntersection(a, b, p6));
+    }
+}
+
+#endif
+
+int main (int argc, char *argv[]) try
+{
+    // maybe initialize mpi
+    Dune::MPIHelper::instance(argc, argv);
+
+    // collect returns to determine exit code
+    std::vector<bool> returns;
+
+    // test for dimWorld = 2
+    testIntersections<2>(returns);
+
+    // test for dimWorld = 3
+    testIntersections<3>(returns);
+
+    // determine the exit code
+    if (std::any_of(returns.begin(), returns.end(), [](bool i){ return !i; }))
+        return 1;
+
+    std::cout << "All tests passed!" << std::endl;
+
+    return 0;
+}
+// //////////////////////////////////
+//   Error handler
+// /////////////////////////////////
+catch (const Dune::Exception& e) {
+    std::cout << e << std::endl;
+    return 1;
+}