Disabled MGS drivers (#537)

* Disabled MGS drivers

Disabled MGS MOC WAC/NAC drivers due to time bias that is not accounted
for in ALE.

* mark mgs wac/nac functions xfail

ale/drivers/__init__.py

@@ -27,7 +27,8 @@ __disabled_drivers__ = ["ody_drivers",
                         "hayabusa2_drivers",
                         "juno_drivers",
                         "tgo_drivers",
-                        "msi_drivers"]
+                        "msi_drivers",
+                        "mgs_drivers"]
 
 # dynamically load drivers
 __all__ = [os.path.splitext(os.path.basename(d))[0] for d in glob(os.path.join(os.path.dirname(__file__), '*_drivers.py'))]

tests/pytests/test_mgs_drivers.py

@@ -20,6 +20,7 @@ def test_nac_kernels():
     for kern in binary_kernels:
         os.remove(kern)
 
+@pytest.mark.xfail
 def test_nac_load(test_nac_kernels):
     label_file = get_image_label('m0402852', 'isis')
     compare_dict = get_isd("mgsmocna")
@@ -38,6 +39,7 @@ def test_wac_kernels():
     for kern in binary_kernels:
         os.remove(kern)
 
+@pytest.mark.xfail
 def test_wac_load(test_wac_kernels):
     label_file = get_image_label('ab102401', 'isis3')
     compare_dict = get_isd("mgsmocwa")