Clean up the output when an unknow type is found

2 files changed, 23 insertions, 2 deletions

diff --git a/jsonschema/exceptions.py b/jsonschema/exceptions.py
index f1d3e42..b24478a 100644
--- a/jsonschema/exceptions.py
+++ b/jsonschema/exceptions.py
@@ -93,7 +93,28 @@ class RefResolutionError(Exception):
 
 
 class UnknownType(Exception):
-    pass
+    def __init__(self, type, instance, schema):
+        self.type = type
+        self.instance = instance
+        self.schema = schema
+        self.msg = "OMGZ"
+
+    def __str__(self):
+        return self.__unicode__()
+
+    def __unicode__(self):
+        pschema = pprint.pformat(self.schema, width=72)
+        pinstance = pprint.pformat(self.instance, width=72)
+        return textwrap.dedent("""
+            unknown type %s, in schema:
+                %r
+
+            On instance:
+                %s
+            """.rstrip()
+        ) % (self.type, self.schema, self.instance)
+
+
 
 
 class FormatError(Exception):
diff --git a/jsonschema/validators.py b/jsonschema/validators.py
index 22abf57..7044428 100644
--- a/jsonschema/validators.py
+++ b/jsonschema/validators.py
@@ -118,7 +118,7 @@ def create(meta_schema, validators=(), version=None, default_types=None):  # noq
 
         def is_type(self, instance, type):
             if type not in self._types:
-                raise UnknownType(type)
+                raise UnknownType(type, instance, self.schema)
             pytypes = self._types[type]
 
             # bool inherits from int, so ensure bools aren't reported as ints