Install vtk with conda if py3.6

.travis.yml

@@ -45,7 +45,8 @@ install:
   - conda install -c conda-forge phonopy
 
   # Mayavi (optional requirement)
-  - if [[ "${PYTHON_VERSION}" == "2.7" ]]; then conda install mayavi; else pip install mayavi; fi
+  - if [[ "${PYTHON_VERSION}" == "2.7" ]]; then conda install mayavi; fi
+  - if [[ "${PYTHON_VERSION}" == "3.6" ]]; then conda install vtk && pip install mayavi; fi
 
   # Get pymatgen from matsci
   - conda config --add channels matsci

abipy/core/tests/test_structure.py

@@ -124,6 +124,9 @@ class TestStructure(AbipyTest):
         if self.has_mayavi():
             si.mayaview(show=False)
 
+        #if self.has_vtk():
+        #    si.vtkview(show=False)
+
         assert si is Structure.as_structure(si)
         assert si == Structure.as_structure(si.to_abivars())
         assert si == Structure.from_abivars(si.to_abivars())

abipy/dynamics/tests/test_hist.py

@@ -64,5 +64,6 @@ class HistFileTest(AbipyTest):
 
         if self.has_mayavi():
             assert hist.mvplot_trajectories(show=False)
+            #assert hist.mvanimate(delay=100)
 
         hist.close()