Fix formatting error for unique items if instance is a tuple

[playpauseandstop]

I have found very uncommon, but still a bug, with formatting error messages for unique items, when instance is a tuple.

Attached a test case to reproduce:

import unittest

from jsonschema.exceptions import ValidationError
from jsonschema.validators import Draft4Validator, validate


TEST_SCHEMA = {
    'type': 'array',
    'items': {
        'type': 'number',
    },
    'minItems': 2,
    'maxItems': 3,
    'uniqueItems': True,
}


TYPES = Draft4Validator.DEFAULT_TYPES.copy()
TYPES['array'] = (list, tuple)


class Validator(Draft4Validator):

    DEFAULT_TYPES = TYPES


class TestItemsErrorMessages(unittest.TestCase):

    array_type = list
    validator_class = Draft4Validator

    def check_error_message(self, instance):
        self.assertRaises(ValidationError,
                          validate,
                          instance,
                          TEST_SCHEMA,
                          self.validator_class)

    def test_min_items(self):
        self.check_error_message(self.array_type([1]))

    def test_max_items(self):
        self.check_error_message(self.array_type([1, 2, 3, 4]))

    def test_unique_items(self):
        self.check_error_message(self.array_type([1, 1, 2]))


class TestItemsErrorMessagesCustomValidator(TestItemsErrorMessages):

    array_type = tuple
    validator_class = Validator


if __name__ == '__main__':
    unittest.main()

Its results:

playpauseandstop@shep:~/Projects/rororo$ env/bin/python ../jsonschema_unique_items.py 
.....E
======================================================================
ERROR: test_unique_items (__main__.TestItemsErrorMessagesCustomValidator)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "../jsonschema_unique_items.py", line 46, in test_unique_items
    self.check_error_message(self.array_type([1, 1, 2]))
  File "../jsonschema_unique_items.py", line 37, in check_error_message
    self.validator_class)
  File "/home/playpauseandstop/.pyenv/versions/3.4.3/lib/python3.4/unittest/case.py", line 704, in assertRaises
    return context.handle('assertRaises', callableObj, args, kwargs)
  File "/home/playpauseandstop/.pyenv/versions/3.4.3/lib/python3.4/unittest/case.py", line 162, in handle
    callable_obj(*args, **kwargs)
  File "/home/playpauseandstop/Projects/rororo/env/lib/python3.4/site-packages/jsonschema/validators.py", line 428, in validate
    cls(schema, *args, **kwargs).validate(instance)
  File "/home/playpauseandstop/Projects/rororo/env/lib/python3.4/site-packages/jsonschema/validators.py", line 116, in validate
    for error in self.iter_errors(*args, **kwargs):
  File "/home/playpauseandstop/Projects/rororo/env/lib/python3.4/site-packages/jsonschema/validators.py", line 95, in iter_errors
    for error in errors:
  File "/home/playpauseandstop/Projects/rororo/env/lib/python3.4/site-packages/jsonschema/_validators.py", line 139, in uniqueItems
    yield ValidationError("%r has non-unique elements" % instance)
TypeError: not all arguments converted during string formatting

----------------------------------------------------------------------
Ran 6 tests in 0.012s

FAILED (errors=1)

And the reason is easy, when formatting min/max items error messages you use '%r' % (instance,) statements, but for unique items don't, so when tuple is an instance, this broken validation message.

[Julian]

Sigh, yup definitely a bug, one-arg str % basically always ends up being one :(.

Could you possibly add your test to the suite as well rather than just here in the ticket? There's already a test case that makes assertions about error messages which should make it I hope not that difficult to add? Otherwise lgtm, thanks so much for filing.

[playpauseandstop]

@Julian

I'm not sure where exactly to put my test case and if it good idea to test against Validator with custom default types. But if it ok, please point me in which exact test case should I move my test case, maybe test_validators:TestValidationErrorDetails?

[playpauseandstop]

FYI, added tests for items errors to jsonschema.tests.test_validators module

[Julian]

Hey, so sorry this took so long for me to merge :( but did so now. Really appreciate the PR.