Tetrahedral remeshing - add a test (#8953)

## Summary of Changes

Add a test that does
```
  c3t3 = make_mesh_3(domain);
  write_MEDIT(file, c3t3);
  read_MEDIT(file, tr);
  tetrahedral_isotropic_remeshing(tr);
```

to test the pipeline.

Adding this test is triggered by issue #8948, but it does not fix it.


## Release Management

* Affected package(s): Tetrahedral_remeshing
* License and copyright ownership:

SMDS_3/include/CGAL/SMDS_3/tet_soup_to_c3t3.h

@@ -566,6 +566,7 @@ bool build_triangulation_from_file(std::istream& is,
 {
   using Point_3 = typename Tr::Point;
   using Subdomain_index = typename Tr::Cell::Subdomain_index;
+  using Surface_patch_index = typename Tr::Cell::Surface_patch_index;
 
   using Facet        = std::array<int, 3>; // 3 = id
   using Tet_with_ref = std::array<int, 4>; // 4 = id
@@ -576,7 +577,7 @@ bool build_triangulation_from_file(std::istream& is,
   std::vector<Tet_with_ref> finite_cells;
   std::vector<Subdomain_index> subdomains;
   std::vector<Point_3> points;
-  boost::unordered_map<Facet, typename Tr::Cell::Surface_patch_index> border_facets;
+  boost::unordered_map<Facet, Surface_patch_index> border_facets;
 
   int dim;
   int nv, nf, ntet, ref;
@@ -632,7 +633,7 @@ bool build_triangulation_from_file(std::istream& is,
     if(line.find("Triangles") != std::string::npos)
     {
       bool has_negative_surface_patch_ids = false;
-      typename Tr::Cell::Surface_patch_index max_surface_patch_id = 0;
+      Surface_patch_index max_surface_patch_id{0};
       is >> nf;
 
       if(verbose)
@@ -641,7 +642,7 @@ bool build_triangulation_from_file(std::istream& is,
       for(int i=0; i<nf; ++i)
       {
         int n[3];
-        typename Tr::Cell::Surface_patch_index surface_patch_id;
+        Surface_patch_index surface_patch_id;
         if(!(is >> n[0] >> n[1] >> n[2] >> surface_patch_id))
         {
           if(verbose)

Tetrahedral_remeshing/test/Tetrahedral_remeshing/CMakeLists.txt

@@ -40,6 +40,9 @@ if(TARGET CGAL::Eigen3_support)
   create_single_source_cgal_program("features_and_adaptive_sizing.cpp")
   target_link_libraries(features_and_adaptive_sizing PRIVATE CGAL::Eigen3_support)
 
+  create_single_source_cgal_program("test_mesh_and_remesh_with_io.cpp")
+  target_link_libraries(test_mesh_and_remesh_with_io PRIVATE CGAL::Eigen3_support)
+
   # with MLS projection
   add_executable(test_mesh_and_remesh_polyhedron_with_features_mls
                 "test_mesh_and_remesh_polyhedron_with_features.cpp")

Tetrahedral_remeshing/test/Tetrahedral_remeshing/test_mesh_and_remesh_with_io.cpp

@@ -0,0 +1,77 @@
+#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
+
+#include <CGAL/Mesh_complex_3_in_triangulation_3.h>
+#include <CGAL/Mesh_criteria_3.h>
+#include <CGAL/Mesh_triangulation_3.h>
+
+#include <CGAL/Image_3.h>
+#include <CGAL/Labeled_mesh_domain_3.h>
+#include <CGAL/make_mesh_3.h>
+
+#include <CGAL/Tetrahedral_remeshing/Remeshing_triangulation_3.h>
+#include <CGAL/tetrahedral_remeshing.h>
+
+#include <CGAL/IO/File_medit.h>
+
+#include <string>
+
+// Domain
+typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
+
+typedef CGAL::Image_3 Image;
+typedef CGAL::Labeled_mesh_domain_3<K> Mesh_domain;
+
+// Triangulation
+typedef CGAL::Mesh_triangulation_3<Mesh_domain>::type Tr;
+typedef CGAL::Mesh_complex_3_in_triangulation_3<Tr> C3t3;
+
+// Mesh Criteria
+typedef CGAL::Mesh_criteria_3<Tr> Mesh_criteria;
+typedef Mesh_criteria::Facet_criteria Facet_criteria;
+typedef Mesh_criteria::Cell_criteria Cell_criteria;
+
+typedef Tr::Geom_traits Gt;
+typedef CGAL::Triangulation_3<Gt, typename Tr::Triangulation_data_structure> T3;
+typedef CGAL::Tetrahedral_remeshing::Remeshing_triangulation_3<Gt> Remeshing_triangulation;
+
+using namespace CGAL::parameters;
+
+int main()
+{
+  const std::string filename = CGAL::data_file_path("images/liver.inr.gz");
+
+  CGAL::Image_3 image;
+  if(!image.read(filename)) {
+    std::cerr << "Error: Cannot read file " << filename << std::endl;
+    return EXIT_FAILURE;
+  }
+  Mesh_domain domain = Mesh_domain::create_labeled_image_mesh_domain(image, relative_error_bound = 1e-9);
+
+  // Mesh criteria
+  Facet_criteria facet_criteria(25, 20, 2); // angle, size, approximation
+  Cell_criteria cell_criteria(3, 20);       // radius-edge ratio, size
+  Mesh_criteria criteria(facet_criteria, cell_criteria);
+
+  // Mesh
+  C3t3 c3t3 = CGAL::make_mesh_3<C3t3>(domain, criteria, no_exude(), no_perturb());
+
+  std::cout << "Meshing done." << std::endl;
+
+  // Write
+  std::ofstream os("after_meshing_io.mesh");
+  CGAL::IO::write_MEDIT(os, c3t3);
+  os.close();
+
+  // Read
+  Remeshing_triangulation tr;
+  std::ifstream is("after_meshing_io.mesh");
+  CGAL::IO::read_MEDIT(is, tr);
+
+  // Remesh
+  double target_edge_length = 10.;
+  CGAL::tetrahedral_isotropic_remeshing(tr, target_edge_length);
+
+  std::cout << "Remeshing done." << std::endl;
+
+  return 0;
+}