Remove usage of deprecated Field.fail on marshmallow 3 (#425)

Author: sloria

CHANGELOG.rst

@@ -1,6 +1,13 @@
 Changelog
 ---------
 
+5.5.1 (unreleased)
+******************
+
+Bug fixes:
+
+* Remove usage of deprecated ``Field.fail`` when using marshmallow 3.
+
 5.5.0 (2019-09-07)
 ******************
 

src/webargs/fields.py

@@ -21,6 +21,7 @@
 
 # Expose all fields from marshmallow.fields.
 from marshmallow.fields import *  # noqa: F40
+from webargs.compat import MARSHMALLOW_VERSION_INFO
 from webargs.dict2schema import dict2schema
 
 __all__ = ["DelimitedList"] + ma.fields.__all__
@@ -73,5 +74,8 @@ def _deserialize(self, value, attr, data, **kwargs):
                 else value.split(self.delimiter)
             )
         except AttributeError:
-            self.fail("invalid")
+            if MARSHMALLOW_VERSION_INFO[0] < 3:
+                self.fail("invalid")
+            else:
+                raise self.make_error("invalid")
         return super(DelimitedList, self)._deserialize(ret, attr, data, **kwargs)