Fixed possible divide by zero in mesh vtk writer and added case to test

src/mesh_common/vtk/VTKMeshWriter.h

@@ -106,7 +106,7 @@ public:
    inline bool isFaceFilterSet()                         const { return static_cast<bool>(faceFilter_);        }
 
    void incrementTimeStep()      { ++timestep_; }
-   bool isWriteScheduled() const { return timestep_ % writeFrequency_ == 0; }
+   bool isWriteScheduled() const { return writeFrequency_ > 0 && timestep_ % writeFrequency_ == 0; }
 
 protected:
    void write( std::ostream & os ) const;

tests/mesh/MeshVTKTest.cpp

@@ -150,6 +150,11 @@ void test( const std::string & meshFile )
    meshWriterStatusfiltered.setFaceFilter( mesh::StatusFaceFilter< MeshType >( OpenMesh::Attributes::TAGGED ) );
 
    meshWriterStatusfiltered();
+
+
+   VTKMeshWriter< MeshType > meshWriterDeactivated( mesh, "mesh_vtk_test_deactivated", 0 );
+
+   meshWriterDeactivated();
 }