Raise ValueError if _get_value called with invalid location

tasks.py

@@ -9,12 +9,14 @@
 build_dir = os.path.join(docs_dir, '_build')
 
 @task
-def test(coverage=False):
+def test(coverage=False, browse=False):
     import pytest
     args = []
     if coverage:
         args.extend(['--cov=webargs', '--cov-report=term', '--cov-report=html'])
     retcode = pytest.main(args)
+    if coverage and browse:
+        webbrowser.open_new_tab(os.path.join('htmlcov', 'index.html'))
     sys.exit(retcode)
 
 @task

tests/test_core.py

@@ -141,7 +141,7 @@ def test_default_can_be_none(parser, web_request):
     assert result['val'] is None
 
 
-def test_value_error_raised_if_invalid_location(web_request):
+def test_value_error_raised_if_parse_arg_called_with_invalid_location(web_request):
     field = fields.Field()
     p = Parser()
     with pytest.raises(ValueError) as excinfo:
@@ -304,6 +304,11 @@ def validate(val):
         parser.parse(args, web_request, locations=('json', ), validate=validate)
     assert excinfo.value.messages == ['Invalid value.']
 
+def test_invalid_argument_for_validate(web_request, parser):
+    with pytest.raises(ValueError) as excinfo:
+        parser.parse({}, web_request, validate='notcallable')
+    assert 'not a callable or list of callables.' in excinfo.value.args[0]
+
 def test_get_value_basic():
     assert get_value({'foo': 42}, 'foo', False) == 42
     assert get_value({'foo': 42}, 'bar', False) is missing

tests/testapp/echo/views.py

@@ -10,7 +10,7 @@
     'name': fields.Str(missing='World')
 }
 hello_multi = {
-    'name': fields.List(fields.Str(), multiple=True)
+    'name': fields.List(fields.Str())
 }
 
 def render_json_response(data):

webargs/core.py

@@ -65,6 +65,7 @@ class Meta(object):
     return cls if not instance else cls(**kwargs)
 
 def is_multiple(field):
+    """Return whether or not `field` handles repeated/multi-value arguments."""
     return isinstance(field, ma.fields.List)
 
 def get_value(d, name, multiple):
@@ -157,7 +158,7 @@ def _get_value(self, name, argobj, req, location):
                 function = getattr(self, func)
             value = function(req, name, argobj)
         else:
-            value = None
+            raise ValueError('Invalid location: "{0}"'.format(location))
         return value
 
     def parse_arg(self, name, field, req, locations=None):