Add a global conftest for doctest

conftest.py

@@ -0,0 +1,35 @@
+"""This runs at the init of the pytest doctest session
+
+Launch or connect to a persistent local DPF service to be shared in
+pytest as a session fixture
+"""
+import re
+import os
+
+import pyvista as pv
+import matplotlib as mpl
+
+# enable off_screen plotting to avoid test interruption
+pv.OFF_SCREEN = True
+mpl.use("Agg")
+
+
+def get_lighting():
+    """Get lighting configuration.
+
+    Disable lighting when using OSMesa on Windows. See:
+    https://github.com/pyvista/pyvista/issues/3185
+
+    """
+    pl = pv.Plotter(notebook=False, off_screen=True)
+    pl.add_mesh(pv.Sphere())
+    pl.show(auto_close=False)
+    gpu_info = pl.ren_win.ReportCapabilities();
+    pl.close()
+
+    regex = re.compile("OpenGL version string:(.+)\n")
+    version = regex.findall(gpu_info)[0]
+    return not(os.name == 'nt' and 'Mesa' in version)
+
+
+pv.global_theme.lighting = get_lighting()