Make it clear when it's a SchemaError vs ValidationError even in the message.

Closes: #352.

Author: Julian

jsonschema/exceptions.py

@@ -67,16 +67,18 @@ def __unicode__(self):
         pinstance = pprint.pformat(self.instance, width=72)
         return self.message + textwrap.dedent("""
 
-            Failed validating %r in schema%s:
+            Failed validating %r in %s%s:
             %s
 
-            On instance%s:
+            On %s%s:
             %s
             """.rstrip()
         ) % (
             self.validator,
+            self._word_for_schema_in_error_message,
             _utils.format_as_index(list(self.relative_schema_path)[:-1]),
             _utils.indent(pschema),
+            self._word_for_instance_in_error_message,
             _utils.format_as_index(self.relative_path),
             _utils.indent(pinstance),
         )
@@ -125,11 +127,13 @@ def _contents(self):
 
 
 class ValidationError(_Error):
-    pass
+    _word_for_schema_in_error_message = "schema"
+    _word_for_instance_in_error_message = "instance"
 
 
 class SchemaError(_Error):
-    pass
+    _word_for_schema_in_error_message = "metaschema"
+    _word_for_instance_in_error_message = "schema"
 
 
 class RefResolutionError(Exception):

jsonschema/tests/test_validators.py

@@ -2,7 +2,7 @@
 from contextlib import contextmanager
 import json
 
-from jsonschema import FormatChecker, ValidationError
+from jsonschema import FormatChecker, SchemaError, ValidationError
 from jsonschema.tests.compat import mock, unittest
 from jsonschema.validators import (
     RefResolutionError, UnknownType, Draft3Validator,
@@ -782,6 +782,22 @@ def test_draft4_validator_is_the_default(self):
             validate({}, {})
             chk_schema.assert_called_once_with({})
 
+    def test_validation_error_message(self):
+        with self.assertRaises(ValidationError) as e:
+            validate(12, {"type": "string"})
+        self.assertRegexpMatches(
+            str(e.exception),
+            "(?s)Failed validating u?'.*' in schema.*On instance",
+        )
+
+    def test_schema_error_message(self):
+        with self.assertRaises(SchemaError) as e:
+            validate(12, {"type": 12})
+        self.assertRegexpMatches(
+            str(e.exception),
+            "(?s)Failed validating u?'.*' in metaschema.*On schema",
+        )
+
 
 class TestRefResolver(unittest.TestCase):