[geometryisection] add test for 1d-2d isection

test/common/geometry/CMakeLists.txt

 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)
 dune_add_test(SOURCES test_graham_convex_hull.cc LABELS unit)
 dune_add_test(SOURCES test_makegeometry.cc LABELS unit)

test/common/geometry/test_1d2d_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 <dune/geometry/multilineargeometry.hh>
+
+#include <dumux/common/geometry/geometryintersection.hh>
+
+
+#ifndef DOXYGEN
+template<int dimworld = 2>
+Dune::MultiLinearGeometry<double, 1, dimworld>
+makeLine(std::initializer_list<Dune::FieldVector<double, dimworld>>&& c)
+{
+    return {Dune::GeometryTypes::line, c};
+}
+
+template<int dimworld = 2>
+bool testIntersection(const Dune::MultiLinearGeometry<double, dimworld, dimworld>& polygon,
+                      const Dune::MultiLinearGeometry<double, 1, dimworld>& line,
+                      bool foundExpected = true)
+{
+    using Test = Dumux::GeometryIntersection<Dune::MultiLinearGeometry<double,dimworld,dimworld>,
+                                             Dune::MultiLinearGeometry<double,1,dimworld> >;
+    typename Test::IntersectionType intersection;
+    bool found = Test::intersection(polygon, line, intersection);
+    if (!found && foundExpected)
+        std::cerr << "Failed detecting intersection with " << line.corner(0) << " " << line.corner(1) << std::endl;
+    else if (found && foundExpected)
+        std::cout << "Found intersection with " << line.corner(0) << " " << line.corner(1) << std::endl;
+    else if (found && !foundExpected)
+        std::cerr << "Found false positive: intersection with " << line.corner(0) << " " << line.corner(1) << std::endl;
+    else if (!found && !foundExpected)
+        std::cout << "No intersection with " << line.corner(0) << " " << line.corner(1) << std::endl;
+    return (found == foundExpected);
+}
+#endif
+
+int main (int argc, char *argv[]) try
+{
+    // maybe initialize mpi
+    Dune::MPIHelper::instance(argc, argv);
+
+    constexpr int dimworld = 2;
+    constexpr int dim = 2;
+
+    // we test quadrilateral-line & triangle-line intersections
+    using CornerStorage = std::vector<Dune::FieldVector<double, dimworld>>;
+    CornerStorage quadCorners({ {0.0, 0.0}, {1.0, 0.0}, {0.0, 1.0}, {1.0, 1.0} });
+    CornerStorage triaCorners({ {0.0, 0.0}, {1.0, 0.0}, {0.0, 1.0} });
+
+    using Geometry = Dune::MultiLinearGeometry<double, dim, dimworld>;
+    Geometry quad(Dune::GeometryTypes::cube(dimworld), quadCorners);
+    Geometry triangle(Dune::GeometryTypes::simplex(dimworld), triaCorners);
+
+    // collect returns to determine exit code
+    std::vector<bool> returns;
+
+    // the tests
+    returns.push_back(testIntersection(quad, makeLine({ {0.0, 0.0}, {1.0, 0.0} })));
+    returns.push_back(testIntersection(quad, makeLine({ {0.0, 0.0}, {0.0, 1.0} })));
+    returns.push_back(testIntersection(quad, makeLine({ {0.0, 0.0}, {1.0, 1.0} })));
+
+    returns.push_back(testIntersection(quad, makeLine({ {1.0, 0.0}, {1.0, 1.0} })));
+    returns.push_back(testIntersection(quad, makeLine({ {1.0, 1.0}, {0.0, 1.0} })));
+
+    returns.push_back(testIntersection(quad, makeLine({ {0.5, 0.0}, {0.5, 1.0} })));
+    returns.push_back(testIntersection(quad, makeLine({ {0.0, 0.5}, {1.0, 0.5} })));
+    returns.push_back(testIntersection(quad, makeLine({ {0.5, 0.5}, {0.5, 2.0} })));
+    returns.push_back(testIntersection(quad, makeLine({ {0.5, 0.5}, {0.5, -2.0} })));
+    returns.push_back(testIntersection(quad, makeLine({ {0.5, 0.5}, {-2.0, 0.5} })));
+    returns.push_back(testIntersection(quad, makeLine({ {0.5, 0.5}, {2.0, 0.5} })));
+
+    returns.push_back(testIntersection(quad, makeLine({ {0.5, 0.0}, {0.5, -2.0} }), false));
+    returns.push_back(testIntersection(quad, makeLine({ {0.5, 1.0}, {0.5, 2.0} }), false));
+
+    returns.push_back(testIntersection(triangle, makeLine({ {0.0, 0.0}, {1.0, 0.0} })));
+    returns.push_back(testIntersection(triangle, makeLine({ {0.0, 0.0}, {0.0, 1.0} })));
+    returns.push_back(testIntersection(triangle, makeLine({ {0.0, 0.0}, {1.0, 1.0} })));
+
+    returns.push_back(testIntersection(triangle, makeLine({ {0.5, 0.0}, {0.5, 1.0} })));
+    returns.push_back(testIntersection(triangle, makeLine({ {0.0, 0.5}, {1.0, 0.5} })));
+    returns.push_back(testIntersection(triangle, makeLine({ {0.5, 0.5}, {0.0, 0.0} })));
+    returns.push_back(testIntersection(triangle, makeLine({ {0.0, 0.0}, {0.5, 0.5} })));
+    returns.push_back(testIntersection(triangle, makeLine({ {0.5, 0.5}, {-2.0, 0.5} })));
+    returns.push_back(testIntersection(triangle, makeLine({ {0.5, 0.5}, {0.5, -2.0} })));
+
+    returns.push_back(testIntersection(triangle, makeLine({ {1.0, 1.0}, {0.0, 1.0} }), false));
+    returns.push_back(testIntersection(triangle, makeLine({ {1.0, 0.0}, {1.0, 1.0} }), false));
+
+    // 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;
+}