Truncated pretty printing

jsonschema/exceptions.py

@@ -3,10 +3,10 @@
 """
 from collections import defaultdict, deque
 import itertools
-import pprint
 import textwrap
 
 import attr
+import prettyprinter
 
 from jsonschema import _utils
 
@@ -15,6 +15,12 @@
 
 _unset = _utils.Unset()
 
+prettyprinter.set_default_config(
+    max_seq_len=5,
+    width=80,
+    depth=3,
+)
+
 
 class _Error(Exception):
     def __init__(
@@ -66,24 +72,24 @@ def __str__(self):
         if any(m is _unset for m in essential_for_verbose):
             return self.message
 
-        pschema = pprint.pformat(self.schema, width=72)
-        pinstance = pprint.pformat(self.instance, width=72)
-        return self.message + textwrap.dedent("""
+        pschema = prettyprinter.pformat(self.schema)
+        pinstance = prettyprinter.pformat(self.instance)
 
-            Failed validating %r in %s%s:
-            %s
+        return textwrap.dedent(
+            """{message}
 
-            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),
+            Failed validating {validator!r} in {schema_word}{schema_path}:\n{schema}
+
+            On {instance_word}{instance_path}:\n{instance}"""
+        ).format(
+            message=self.message,
+            validator=self.validator,
+            schema_word=self._word_for_schema_in_error_message,
+            schema_path=_utils.format_as_index(list(self.relative_schema_path)[:-1]),
+            schema=_utils.indent(pschema, 4),
+            instance_word=self._word_for_instance_in_error_message,
+            instance_path=_utils.format_as_index(self.relative_path),
+            instance=_utils.indent(pinstance, 4),
         )
 
     @classmethod

jsonschema/tests/test_exceptions.py

@@ -298,7 +298,7 @@ def make_error(self, **kwargs):
         return exceptions.ValidationError(**defaults)
 
     def assertShows(self, expected, **kwargs):
-        expected = textwrap.dedent(expected).rstrip("\n")
+        expected = expected.rstrip("\n")
 
         error = self.make_error(**kwargs)
         message_line, _, rest = str(error).partition("\n")
@@ -339,8 +339,7 @@ def test_empty_paths(self):
                 {'type': 'string'}
 
             On instance:
-                5
-            """,
+                5""",
             path=[],
             schema_path=[],
         )
@@ -352,8 +351,7 @@ def test_one_item_paths(self):
                 {'type': 'string'}
 
             On instance[0]:
-                5
-            """,
+                5""",
             path=[0],
             schema_path=["items"],
         )
@@ -365,8 +363,7 @@ def test_multiple_item_paths(self):
                 {'type': 'string'}
 
             On instance[0]['a']:
-                5
-            """,
+                5""",
             path=[0, u"a"],
             schema_path=[u"items", 0, 1],
         )
@@ -375,54 +372,25 @@ def test_uses_pprint(self):
         self.assertShows(
             """
             Failed validating 'maxLength' in schema:
-                {0: 0,
-                 1: 1,
-                 2: 2,
-                 3: 3,
-                 4: 4,
-                 5: 5,
-                 6: 6,
-                 7: 7,
-                 8: 8,
-                 9: 9,
-                 10: 10,
-                 11: 11,
-                 12: 12,
-                 13: 13,
-                 14: 14,
-                 15: 15,
-                 16: 16,
-                 17: 17,
-                 18: 18,
-                 19: 19}
+                {
+                    0: 0,
+                    1: 1,
+                    2: 2,
+                    3: 3,
+                    4: 4
+                    # ...and 15 more elements
+                }
 
             On instance:
-                [0,
-                 1,
-                 2,
-                 3,
-                 4,
-                 5,
-                 6,
-                 7,
-                 8,
-                 9,
-                 10,
-                 11,
-                 12,
-                 13,
-                 14,
-                 15,
-                 16,
-                 17,
-                 18,
-                 19,
-                 20,
-                 21,
-                 22,
-                 23,
-                 24]
-            """,
+                [
+                    0,
+                    1,
+                    2,
+                    3,
+                    4,
+                    # ...and 20 more elements
+                ]""",
+
             instance=list(range(25)),
             schema=dict(zip(range(20), range(20))),
             validator=u"maxLength",

setup.cfg

@@ -29,6 +29,7 @@ install_requires =
     functools32;python_version<'3'
     importlib_metadata;python_version<'3.8'
     pyrsistent>=0.14.0
+    prettyprinter
 
 [options.extras_require]
 format =