FEM: unit tests, add tetra10 vtk mesh read and write test

src/Mod/Fem/CMakeLists.txt

@@ -168,6 +168,7 @@ SET(FemTestsMesh_SRCS
     femtest/testfiles/mesh/__init__.py
     femtest/testfiles/mesh/tetra10_mesh.inp
     femtest/testfiles/mesh/tetra10_mesh.unv
+    femtest/testfiles/mesh/tetra10_mesh.vtk
     femtest/testfiles/mesh/tetra10_mesh.z88
 )
 

src/Mod/Fem/femtest/testfiles/mesh/tetra10_mesh.vtk

@@ -0,0 +1,15 @@
+# vtk DataFile Version 4.0
+vtk output
+ASCII
+DATASET UNSTRUCTURED_GRID
+POINTS 10 float
+6 12 18 0 0 18 12 0 18 
+6 6 0 3 6 18 6 0 18 
+9 6 18 6 9 9 3 3 9 
+9 3 9 
+CELLS 1 11
+10 0 1 2 3 4 5 6 7 8 9 
+
+CELL_TYPES 1
+24
+

src/Mod/Fem/femtest/testmesh.py

@@ -305,6 +305,50 @@ class TestMeshEleTetra10(unittest.TestCase):
             "Test writing " + self.elem + " mesh to " + filetyp + " file failed. Volumes are different.\n"
         )
 
+    def test_tetra10_vkt(self):
+        # tetra10 element: reading from and writing to unv mesh file format
+        filetyp = 'vtk'
+        outfile = self.base_outfile + filetyp
+        testfile = self.base_testfile + filetyp
+        # fcc_print(outfile)
+        # fcc_print(testfile)
+        self.femmesh.write(outfile)  # write the mesh
+        femmesh_outfile = Fem.read(outfile)  # read the mesh from written mesh
+        femmesh_testfile = Fem.read(testfile)  # read the mesh from test mesh
+        # reading the test mesh
+        self.assertEqual(
+            femmesh_testfile.Nodes,
+            self.expected_nodes['nodes'],
+            "Test writing " + self.elem + " mesh to " + filetyp + " file failed. Nodes are different.\n"
+        )
+        self.assertEqual(
+            [femmesh_testfile.Volumes[0], femmesh_testfile.getElementNodes(femmesh_outfile.Volumes[0])],
+            self.expected_elem['volumes'],
+            "Test writing " + self.elem + " mesh to " + filetyp + " file failed. Volumes are different.\n"
+        )
+        # reading the written mesh
+        self.assertEqual(
+            femmesh_outfile.Nodes,
+            self.expected_nodes['nodes'],
+            "Test writing " + self.elem + " mesh to " + filetyp + " file failed. Nodes are different.\n"
+        )
+        self.assertEqual(
+            [femmesh_outfile.Volumes[0], femmesh_outfile.getElementNodes(femmesh_outfile.Volumes[0])],
+            self.expected_elem['volumes'],
+            "Test writing " + self.elem + " mesh to " + filetyp + " file failed. Volumes are different.\n"
+        )
+        # both
+        self.assertEqual(
+            femmesh_outfile.Nodes,
+            femmesh_testfile.Nodes,
+            "Test writing " + self.elem + " mesh to " + filetyp + " file failed. Nodes are different.\n"
+        )
+        self.assertEqual(
+            femmesh_outfile.Volumes,
+            femmesh_testfile.Volumes,
+            "Test writing " + self.elem + " mesh to " + filetyp + " file failed. Volumes are different.\n"
+        )
+
     def test_tetra10_z88(self):
         # tetra10 element: reading from and writing to z88 mesh file format
         filetyp = 'z88'