Move tests into package.

5 files changed, 1043 insertions, 0 deletions

diff --git a/jsonschema/tests/__init__.py b/jsonschema/tests/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/jsonschema/tests/__init__.py
diff --git a/jsonschema/tests/compat.py b/jsonschema/tests/compat.py
new file mode 100644
index 0000000..b37483f
--- /dev/null
+++ b/jsonschema/tests/compat.py
@@ -0,0 +1,15 @@
+import sys
+
+
+if sys.version_info[:2] < (2, 7):  # pragma: no cover
+    import unittest2 as unittest
+else:
+    import unittest
+
+try:
+    from unittest import mock
+except ImportError:
+    import mock
+
+
+# flake8: noqa
diff --git a/jsonschema/tests/test_format.py b/jsonschema/tests/test_format.py
new file mode 100644
index 0000000..e7576b4
--- /dev/null
+++ b/jsonschema/tests/test_format.py
@@ -0,0 +1,58 @@
+from jsonschema.tests.compat import mock, unittest
+
+from jsonschema import FormatError, ValidationError, FormatChecker
+from jsonschema.validators import Draft4Validator
+
+
+class TestFormatChecker(unittest.TestCase):
+    def setUp(self):
+        self.fn = mock.Mock()
+
+    def test_it_can_validate_no_formats(self):
+        checker = FormatChecker(formats=())
+        self.assertFalse(checker.checkers)
+
+    def test_it_raises_a_key_error_for_unknown_formats(self):
+        with self.assertRaises(KeyError):
+            FormatChecker(formats=["o noes"])
+
+    def test_it_can_register_cls_checkers(self):
+        with mock.patch.dict(FormatChecker.checkers, clear=True):
+            FormatChecker.cls_checks("new")(self.fn)
+            self.assertEqual(FormatChecker.checkers, {"new" : (self.fn, ())})
+
+    def test_it_can_register_checkers(self):
+        checker = FormatChecker()
+        checker.checks("new")(self.fn)
+        self.assertEqual(
+            checker.checkers,
+            dict(FormatChecker.checkers, new=(self.fn, ()))
+        )
+
+    def test_it_catches_registered_errors(self):
+        checker = FormatChecker()
+        cause = self.fn.side_effect = ValueError()
+
+        checker.checks("foo", raises=ValueError)(self.fn)
+
+        with self.assertRaises(FormatError) as cm:
+            checker.check("bar", "foo")
+
+        self.assertIs(cm.exception.cause, cause)
+        self.assertIs(cm.exception.__cause__, cause)
+
+        # Unregistered errors should not be caught
+        self.fn.side_effect = AttributeError
+        with self.assertRaises(AttributeError):
+            checker.check("bar", "foo")
+
+    def test_format_error_causes_become_validation_error_causes(self):
+        checker = FormatChecker()
+        checker.checks("foo", raises=ValueError)(self.fn)
+        cause = self.fn.side_effect = ValueError()
+        validator = Draft4Validator({"format" : "foo"}, format_checker=checker)
+
+        with self.assertRaises(ValidationError) as cm:
+            validator.validate("bar")
+
+        self.assertIs(cm.exception.__cause__, cause)
diff --git a/jsonschema/tests/test_jsonschema_test_suite.py b/jsonschema/tests/test_jsonschema_test_suite.py
new file mode 100644
index 0000000..b9c3c95
--- /dev/null
+++ b/jsonschema/tests/test_jsonschema_test_suite.py
@@ -0,0 +1,236 @@
+from decimal import Decimal
+import glob
+import json
+import io
+import itertools
+import os
+import re
+import subprocess
+
+try:
+    from sys import pypy_version_info
+except ImportError:
+    pypy_version_info = None
+
+from jsonschema import (
+    FormatError, SchemaError, ValidationError, Draft3Validator,
+    Draft4Validator, FormatChecker, draft3_format_checker,
+    draft4_format_checker, validate,
+)
+from jsonschema.compat import PY3
+from jsonschema.tests.compat import mock, unittest
+import jsonschema
+
+
+REPO_ROOT = os.path.join(os.path.dirname(jsonschema.__file__), os.path.pardir)
+SUITE = os.getenv("JSON_SCHEMA_TEST_SUITE", os.path.join(REPO_ROOT, "json"))
+
+if not os.path.isdir(SUITE):
+    raise ValueError(
+        "Can't find the JSON-Schema-Test-Suite directory. Set the "
+        "'JSON_SCHEMA_TEST_SUITE' environment variable or run the tests from "
+        "alongside a checkout of the suite."
+    )
+
+TESTS_DIR = os.path.join(SUITE, "tests")
+JSONSCHEMA_SUITE = os.path.join(SUITE, "bin", "jsonschema_suite")
+
+REMOTES = subprocess.Popen(
+    ["python", JSONSCHEMA_SUITE, "remotes"], stdout=subprocess.PIPE,
+).stdout
+if PY3:
+    REMOTES = io.TextIOWrapper(REMOTES)
+REMOTES = json.load(REMOTES)
+
+
+def make_case(schema, data, valid):
+    if valid:
+        def test_case(self):
+            kwargs = getattr(self, "validator_kwargs", {})
+            validate(data, schema, cls=self.validator_class, **kwargs)
+    else:
+        def test_case(self):
+            kwargs = getattr(self, "validator_kwargs", {})
+            with self.assertRaises(ValidationError):
+                validate(data, schema, cls=self.validator_class, **kwargs)
+    return test_case
+
+
+def load_json_cases(tests_glob, ignore_glob="", basedir=TESTS_DIR, skip=None):
+    if ignore_glob:
+        ignore_glob = os.path.join(basedir, ignore_glob)
+
+    def add_test_methods(test_class):
+        ignored = set(glob.iglob(ignore_glob))
+
+        for filename in glob.iglob(os.path.join(basedir, tests_glob)):
+            if filename in ignored:
+                continue
+
+            validating, _ = os.path.splitext(os.path.basename(filename))
+            id = itertools.count(1)
+
+            with open(filename) as test_file:
+                data = json.load(test_file)
+
+                for case in data:
+                    for test in case["tests"]:
+                        a_test = make_case(
+                            case["schema"],
+                            test["data"],
+                            test["valid"],
+                        )
+
+                        test_name = "test_%s_%s_%s" % (
+                            validating,
+                            next(id),
+                            re.sub(r"[\W ]+", "_", test["description"]),
+                        )
+
+                        if not PY3:
+                            test_name = test_name.encode("utf-8")
+                        a_test.__name__ = test_name
+
+                        if skip is not None and skip(case):
+                            a_test = unittest.skip("Checker not present.")(
+                                a_test
+                            )
+
+                        assert not hasattr(test_class, test_name), test_name
+                        setattr(test_class, test_name, a_test)
+
+        return test_class
+    return add_test_methods
+
+
+class TypesMixin(object):
+    @unittest.skipIf(PY3, "In Python 3 json.load always produces unicode")
+    def test_string_a_bytestring_is_a_string(self):
+        self.validator_class({"type" : "string"}).validate(b"foo")
+
+
+class DecimalMixin(object):
+    def test_it_can_validate_with_decimals(self):
+        schema = {"type" : "number"}
+        validator = self.validator_class(
+            schema, types={"number" : (int, float, Decimal)}
+        )
+
+        for valid in [1, 1.1, Decimal(1) / Decimal(8)]:
+            validator.validate(valid)
+
+        for invalid in ["foo", {}, [], True, None]:
+            with self.assertRaises(ValidationError):
+                validator.validate(invalid)
+
+
+def missing_format(checker):
+    def missing_format(case):
+        format = case["schema"].get("format")
+        return format not in checker.checkers or (
+            # datetime.datetime is overzealous about typechecking in <=1.9
+            format == "date-time" and
+            pypy_version_info is not None and
+            pypy_version_info[:2] <= (1, 9)
+        )
+    return missing_format
+
+
+class FormatMixin(object):
+    def test_it_returns_true_for_formats_it_does_not_know_about(self):
+        validator = self.validator_class(
+            {"format" : "carrot"}, format_checker=FormatChecker(),
+        )
+        validator.validate("bugs")
+
+    def test_it_does_not_validate_formats_by_default(self):
+        validator = self.validator_class({})
+        self.assertIsNone(validator.format_checker)
+
+    def test_it_validates_formats_if_a_checker_is_provided(self):
+        checker = mock.Mock(spec=FormatChecker)
+        validator = self.validator_class(
+            {"format" : "foo"}, format_checker=checker,
+        )
+
+        validator.validate("bar")
+
+        checker.check.assert_called_once_with("bar", "foo")
+
+        cause = ValueError()
+        checker.check.side_effect = FormatError('aoeu', cause=cause)
+
+        with self.assertRaises(ValidationError) as cm:
+            validator.validate("bar")
+        # Make sure original cause is attached
+        self.assertIs(cm.exception.cause, cause)
+
+
+@load_json_cases("draft3/*.json", ignore_glob="draft3/refRemote.json")
+@load_json_cases(
+    "draft3/optional/format.json", skip=missing_format(draft3_format_checker)
+)
+@load_json_cases("draft3/optional/bignum.json")
+@load_json_cases("draft3/optional/zeroTerminatedFloats.json")
+class TestDraft3(unittest.TestCase, TypesMixin, DecimalMixin, FormatMixin):
+    validator_class = Draft3Validator
+    validator_kwargs = {"format_checker" : draft3_format_checker}
+
+    def test_any_type_is_valid_for_type_any(self):
+        validator = self.validator_class({"type" : "any"})
+        validator.validate(mock.Mock())
+
+    # TODO: we're in need of more meta schema tests
+    def test_invalid_properties(self):
+        with self.assertRaises(SchemaError):
+            validate({}, {"properties": {"test": True}},
+                     cls=self.validator_class)
+
+    def test_minItems_invalid_string(self):
+        with self.assertRaises(SchemaError):
+            # needs to be an integer
+            validate([1], {"minItems" : "1"}, cls=self.validator_class)
+
+
+@load_json_cases("draft4/*.json", ignore_glob="draft4/refRemote.json")
+@load_json_cases(
+    "draft4/optional/format.json", skip=missing_format(draft4_format_checker)
+)
+@load_json_cases("draft4/optional/bignum.json")
+@load_json_cases("draft4/optional/zeroTerminatedFloats.json")
+class TestDraft4(unittest.TestCase, TypesMixin, DecimalMixin, FormatMixin):
+    validator_class = Draft4Validator
+    validator_kwargs = {"format_checker" : draft4_format_checker}
+
+    # TODO: we're in need of more meta schema tests
+    def test_invalid_properties(self):
+        with self.assertRaises(SchemaError):
+            validate({}, {"properties": {"test": True}},
+                     cls=self.validator_class)
+
+    def test_minItems_invalid_string(self):
+        with self.assertRaises(SchemaError):
+            # needs to be an integer
+            validate([1], {"minItems" : "1"}, cls=self.validator_class)
+
+
+class RemoteRefResolutionMixin(object):
+    def setUp(self):
+        patch = mock.patch("jsonschema.validators.requests")
+        requests = patch.start()
+        requests.get.side_effect = self.resolve
+        self.addCleanup(patch.stop)
+
+    def resolve(self, reference):
+        _, _, reference = reference.partition("http://localhost:1234/")
+        return mock.Mock(**{"json.return_value" : REMOTES.get(reference)})
+
+
+@load_json_cases("draft3/refRemote.json")
+class Draft3RemoteResolution(RemoteRefResolutionMixin, unittest.TestCase):
+    validator_class = Draft3Validator
+
+
+@load_json_cases("draft4/refRemote.json")
+class Draft4RemoteResolution(RemoteRefResolutionMixin, unittest.TestCase):
+    validator_class = Draft4Validator
diff --git a/jsonschema/tests/test_validators.py b/jsonschema/tests/test_validators.py
new file mode 100644
index 0000000..2fd1d91
--- /dev/null
+++ b/jsonschema/tests/test_validators.py
@@ -0,0 +1,734 @@
+from __future__ import unicode_literals
+import contextlib
+import json
+import pprint
+import textwrap
+
+from jsonschema import FormatChecker
+from jsonschema.compat import PY3
+from jsonschema.tests.compat import mock, unittest
+from jsonschema.validators import (
+    RefResolutionError, UnknownType, ValidationError, ErrorTree,
+    Draft3Validator, Draft4Validator, RefResolver, ValidatorMixin, validate,
+)
+
+
+class TestIterErrors(unittest.TestCase):
+    def setUp(self):
+        self.validator = Draft3Validator({})
+
+    def test_iter_errors(self):
+        instance = [1, 2]
+        schema = {
+            "disallow" : "array",
+            "enum" : [["a", "b", "c"], ["d", "e", "f"]],
+            "minItems" : 3
+        }
+
+        got = (e.message for e in self.validator.iter_errors(instance, schema))
+        expected = [
+            "%r is disallowed for [1, 2]" % (schema["disallow"],),
+            "[1, 2] is too short",
+            "[1, 2] is not one of %r" % (schema["enum"],),
+        ]
+        self.assertEqual(sorted(got), sorted(expected))
+
+    def test_iter_errors_multiple_failures_one_validator(self):
+        instance = {"foo" : 2, "bar" : [1], "baz" : 15, "quux" : "spam"}
+        schema = {
+            "properties" : {
+                "foo" : {"type" : "string"},
+                "bar" : {"minItems" : 2},
+                "baz" : {"maximum" : 10, "enum" : [2, 4, 6, 8]},
+            }
+        }
+
+        errors = list(self.validator.iter_errors(instance, schema))
+        self.assertEqual(len(errors), 4)
+
+
+class TestValidationErrorMessages(unittest.TestCase):
+    def message_for(self, instance, schema, *args, **kwargs):
+        kwargs.setdefault("cls", Draft3Validator)
+        with self.assertRaises(ValidationError) as e:
+            validate(instance, schema, *args, **kwargs)
+        return e.exception.message
+
+    def test_single_type_failure(self):
+        message = self.message_for(instance=1, schema={"type" : "string"})
+        self.assertEqual(message, "1 is not of type %r" % "string")
+
+    def test_single_type_list_failure(self):
+        message = self.message_for(instance=1, schema={"type" : ["string"]})
+        self.assertEqual(message, "1 is not of type %r" % "string")
+
+    def test_multiple_type_failure(self):
+        types = ("string", "object")
+        message = self.message_for(instance=1, schema={"type" : list(types)})
+        self.assertEqual(message, "1 is not of type %r, %r" % types)
+
+    def test_object_without_title_type_failure(self):
+        type = {"type" : [{"minimum" : 3}]}
+        message = self.message_for(instance=1, schema={"type" : [type]})
+        self.assertEqual(message, "1 is not of type %r" % (type,))
+
+    def test_object_with_name_type_failure(self):
+        name = "Foo"
+        schema = {"type" : [{"name" : name, "minimum" : 3}]}
+        message = self.message_for(instance=1, schema=schema)
+        self.assertEqual(message, "1 is not of type %r" % (name,))
+
+    def test_dependencies_failure_has_single_element_not_list(self):
+        depend, on = "bar", "foo"
+        schema = {"dependencies" : {depend : on}}
+        message = self.message_for({"bar" : 2}, schema)
+        self.assertEqual(message, "%r is a dependency of %r" % (on, depend))
+
+    def test_additionalItems_single_failure(self):
+        message = self.message_for(
+            [2], {"items" : [], "additionalItems" : False},
+        )
+        self.assertIn("(2 was unexpected)", message)
+
+    def test_additionalItems_multiple_failures(self):
+        message = self.message_for(
+            [1, 2, 3], {"items" : [], "additionalItems" : False}
+        )
+        self.assertIn("(1, 2, 3 were unexpected)", message)
+
+    def test_additionalProperties_single_failure(self):
+        additional = "foo"
+        schema = {"additionalProperties" : False}
+        message = self.message_for({additional : 2}, schema)
+        self.assertIn("(%r was unexpected)" % (additional,), message)
+
+    def test_additionalProperties_multiple_failures(self):
+        schema = {"additionalProperties" : False}
+        message = self.message_for(dict.fromkeys(["foo", "bar"]), schema)
+
+        self.assertIn(repr("foo"), message)
+        self.assertIn(repr("bar"), message)
+        self.assertIn("were unexpected)", message)
+
+    def test_invalid_format_default_message(self):
+        checker = FormatChecker(formats=())
+        check_fn = mock.Mock(return_value=False)
+        checker.checks("thing")(check_fn)
+
+        schema = {"format" : "thing"}
+        message = self.message_for("bla", schema, format_checker=checker)
+
+        self.assertIn(repr("bla"), message)
+        self.assertIn(repr("thing"), message)
+        self.assertIn("is not a", message)
+
+
+class TestErrorReprStr(unittest.TestCase):
+
+    message = "hello"
+
+    def setUp(self):
+        self.error = ValidationError(
+            message=self.message,
+            validator="type",
+            validator_value="string",
+            instance=5,
+            schema={"type" : "string"},
+        )
+
+    def assertShows(self, message):
+        if PY3:
+            message = message.replace("u'", "'")
+        message = textwrap.dedent(message).rstrip("\n")
+
+        message_line, _, rest = str(self.error).partition("\n")
+        self.assertEqual(message_line, self.message)
+        self.assertEqual(rest, message)
+
+    def test_repr(self):
+        self.assertEqual(
+            repr(self.error),
+            "<ValidationError: %r>" % self.message,
+        )
+
+    def test_unset_error(self):
+        error = ValidationError("message")
+        self.assertEqual(str(error), "message")
+
+        kwargs = {
+            "validator": "type",
+            "validator_value": "string",
+            "instance": 5,
+            "schema": {"type": "string"}
+        }
+        # Just the message should show if any of the attributes are unset
+        for attr in kwargs:
+            k = dict(kwargs)
+            del k[attr]
+            error = ValidationError("message", **k)
+            self.assertEqual(str(error), "message")
+
+    def test_empty_paths(self):
+        self.error.path = self.error.schema_path = []
+        self.assertShows(
+            """
+            Failed validating u'type' in schema:
+                {u'type': u'string'}
+
+            On instance:
+                5
+            """
+        )
+
+    def test_one_item_paths(self):
+        self.error.path = [0]
+        self.error.schema_path = ["items"]
+        self.assertShows(
+            """
+            Failed validating u'type' in schema:
+                {u'type': u'string'}
+
+            On instance[0]:
+                5
+            """
+        )
+
+    def test_multiple_item_paths(self):
+        self.error.path = [0, "a"]
+        self.error.schema_path = ["items", 0, 1]
+        self.assertShows(
+            """
+            Failed validating u'type' in schema[u'items'][0]:
+                {u'type': u'string'}
+
+            On instance[0][u'a']:
+                5
+            """
+        )
+
+    def test_uses_pprint(self):
+        with mock.patch.object(pprint, "pformat") as pformat:
+            str(self.error)
+            self.assertGreater(pformat.call_count, 1)  # schema + instance
+
+
+class TestValidationErrorDetails(unittest.TestCase):
+    # TODO: These really need unit tests for each individual validator, rather
+    #       than just these higher level tests.
+    def test_anyOf(self):
+        instance = 5
+        schema = {
+            "anyOf": [
+                {"minimum": 20},
+                {"type": "string"}
+            ]
+        }
+
+        validator = Draft4Validator(schema)
+        errors = list(validator.iter_errors(instance))
+        self.assertEqual(len(errors), 1)
+        e = errors[0]
+
+        self.assertEqual(e.validator, "anyOf")
+        self.assertEqual(list(e.schema_path), ["anyOf"])
+        self.assertEqual(e.validator_value, schema["anyOf"])
+        self.assertEqual(e.instance, instance)
+        self.assertEqual(e.schema, schema)
+        self.assertEqual(list(e.path), [])
+        self.assertEqual(len(e.context), 2)
+
+        e1, e2 = sorted_errors(e.context)
+
+        self.assertEqual(e1.validator, "minimum")
+        self.assertEqual(list(e1.schema_path), [0, "minimum"])
+        self.assertEqual(e1.validator_value, schema["anyOf"][0]["minimum"])
+        self.assertEqual(e1.instance, instance)
+        self.assertEqual(e1.schema, schema["anyOf"][0])
+        self.assertEqual(list(e1.path), [])
+        self.assertEqual(len(e1.context), 0)
+
+        self.assertEqual(e2.validator, "type")
+        self.assertEqual(list(e2.schema_path), [1, "type"])
+        self.assertEqual(e2.validator_value, schema["anyOf"][1]["type"])
+        self.assertEqual(e2.instance, instance)
+        self.assertEqual(e2.schema, schema["anyOf"][1])
+        self.assertEqual(list(e2.path), [])
+        self.assertEqual(len(e2.context), 0)
+
+    def test_type(self):
+        instance = {"foo": 1}
+        schema = {
+            "type": [
+                {"type": "integer"},
+                {
+                    "type": "object",
+                    "properties": {
+                        "foo": {"enum": [2]}
+                    }
+                }
+            ]
+        }
+
+        validator = Draft3Validator(schema)
+        errors = list(validator.iter_errors(instance))
+        self.assertEqual(len(errors), 1)
+        e = errors[0]
+
+        self.assertEqual(e.validator, "type")
+        self.assertEqual(list(e.schema_path), ["type"])
+        self.assertEqual(e.validator_value, schema["type"])
+        self.assertEqual(e.instance, instance)
+        self.assertEqual(e.schema, schema)
+        self.assertEqual(list(e.path), [])
+        self.assertEqual(len(e.context), 2)
+
+        e1, e2 = sorted_errors(e.context)
+
+        self.assertEqual(e1.validator, "type")
+        self.assertEqual(list(e1.schema_path), [0, "type"])
+        self.assertEqual(e1.validator_value, schema["type"][0]["type"])
+        self.assertEqual(e1.instance, instance)
+        self.assertEqual(e1.schema, schema["type"][0])
+        self.assertEqual(list(e1.path), [])
+        self.assertEqual(len(e1.context), 0)
+
+        self.assertEqual(e2.validator, "enum")
+        self.assertEqual(
+            list(e2.schema_path),
+            [1, "properties", "foo", "enum"]
+        )
+        self.assertEqual(
+            e2.validator_value,
+            schema["type"][1]["properties"]["foo"]["enum"]
+        )
+        self.assertEqual(e2.instance, instance["foo"])
+        self.assertEqual(e2.schema, schema["type"][1]["properties"]["foo"])
+        self.assertEqual(list(e2.path), ["foo"])
+        self.assertEqual(len(e2.context), 0)
+
+    def test_single_nesting(self):
+        instance = {"foo" : 2, "bar" : [1], "baz" : 15, "quux" : "spam"}
+        schema = {
+            "properties" : {
+                "foo" : {"type" : "string"},
+                "bar" : {"minItems" : 2},
+                "baz" : {"maximum" : 10, "enum" : [2, 4, 6, 8]},
+            }
+        }
+
+        validator = Draft3Validator(schema)
+        errors = validator.iter_errors(instance)
+        e1, e2, e3, e4 = sorted_errors(errors)
+
+        self.assertEqual(list(e1.path), ["bar"])
+        self.assertEqual(list(e2.path), ["baz"])
+        self.assertEqual(list(e3.path), ["baz"])
+        self.assertEqual(list(e4.path), ["foo"])
+
+        self.assertEqual(e1.validator, "minItems")
+        self.assertEqual(e2.validator, "enum")
+        self.assertEqual(e3.validator, "maximum")
+        self.assertEqual(e4.validator, "type")
+
+    def test_multiple_nesting(self):
+        instance = [1, {"foo" : 2, "bar" : {"baz" : [1]}}, "quux"]
+        schema = {
+            "type" : "string",
+            "items" : {
+                "type" : ["string", "object"],
+                "properties" : {
+                    "foo" : {"enum" : [1, 3]},
+                    "bar" : {
+                        "type" : "array",
+                        "properties" : {
+                            "bar" : {"required" : True},
+                            "baz" : {"minItems" : 2},
+                        }
+                    }
+                }
+            }
+        }
+
+        validator = Draft3Validator(schema)
+        errors = validator.iter_errors(instance)
+        e1, e2, e3, e4, e5, e6 = sorted_errors(errors)
+
+        self.assertEqual(list(e1.path), [])
+        self.assertEqual(list(e2.path), [0])
+        self.assertEqual(list(e3.path), [1, "bar"])
+        self.assertEqual(list(e4.path), [1, "bar", "bar"])
+        self.assertEqual(list(e5.path), [1, "bar", "baz"])
+        self.assertEqual(list(e6.path), [1, "foo"])
+
+        self.assertEqual(e1.validator, "type")
+        self.assertEqual(e2.validator, "type")
+        self.assertEqual(e3.validator, "type")
+        self.assertEqual(e4.validator, "required")
+        self.assertEqual(e5.validator, "minItems")
+        self.assertEqual(e6.validator, "enum")
+
+    def test_additionalProperties(self):
+        instance = {"bar": "bar", "foo": 2}
+        schema = {
+            "additionalProperties" : {"type": "integer", "minimum": 5}
+        }
+
+        validator = Draft3Validator(schema)
+        errors = validator.iter_errors(instance)
+        e1, e2 = sorted_errors(errors)
+
+        self.assertEqual(list(e1.path), ["bar"])
+        self.assertEqual(list(e2.path), ["foo"])
+
+        self.assertEqual(e1.validator, "type")
+        self.assertEqual(e2.validator, "minimum")
+
+    def test_patternProperties(self):
+        instance = {"bar": 1, "foo": 2}
+        schema = {
+            "patternProperties" : {
+                "bar": {"type": "string"},
+                "foo": {"minimum": 5}
+            }
+        }
+
+        validator = Draft3Validator(schema)
+        errors = validator.iter_errors(instance)
+        e1, e2 = sorted_errors(errors)
+
+        self.assertEqual(list(e1.path), ["bar"])
+        self.assertEqual(list(e2.path), ["foo"])
+
+        self.assertEqual(e1.validator, "type")
+        self.assertEqual(e2.validator, "minimum")
+
+    def test_additionalItems(self):
+        instance = ["foo", 1]
+        schema = {
+            "items": [],
+            "additionalItems" : {"type": "integer", "minimum": 5}
+        }
+
+        validator = Draft3Validator(schema)
+        errors = validator.iter_errors(instance)
+        e1, e2 = sorted_errors(errors)
+
+        self.assertEqual(list(e1.path), [0])
+        self.assertEqual(list(e2.path), [1])
+
+        self.assertEqual(e1.validator, "type")
+        self.assertEqual(e2.validator, "minimum")
+
+
+class TestErrorTree(unittest.TestCase):
+    def setUp(self):
+        self.validator = Draft3Validator({})
+
+    def test_it_knows_how_many_total_errors_it_contains(self):
+        errors = [mock.MagicMock() for _ in range(8)]
+        tree = ErrorTree(errors)
+        self.assertEqual(tree.total_errors, 8)
+
+    def test_it_contains_an_item_if_the_item_had_an_error(self):
+        errors = [ValidationError("a message", path=["bar"])]
+        tree = ErrorTree(errors)
+        self.assertIn("bar", tree)
+
+    def test_it_does_not_contain_an_item_if_the_item_had_no_error(self):
+        errors = [ValidationError("a message", path=["bar"])]
+        tree = ErrorTree(errors)
+        self.assertNotIn("foo", tree)
+
+    def test_validators_that_failed_appear_in_errors_dict(self):
+        error = ValidationError("a message", validator="foo")
+        tree = ErrorTree([error])
+        self.assertEqual(tree.errors, {"foo" : error})
+
+    def test_it_creates_a_child_tree_for_each_nested_path(self):
+        errors = [
+            ValidationError("a bar message", path=["bar"]),
+            ValidationError("a bar -> 0 message", path=["bar", 0]),
+        ]
+        tree = ErrorTree(errors)
+        self.assertIn(0, tree["bar"])
+        self.assertNotIn(1, tree["bar"])
+
+    def test_children_have_their_errors_dicts_built(self):
+        e1, e2 = (
+            ValidationError("message 1", validator="foo", path=["bar", 0]),
+            ValidationError("message 2", validator="quux", path=["bar", 0]),
+        )
+        tree = ErrorTree([e1, e2])
+        self.assertEqual(tree["bar"][0].errors, {"foo" : e1, "quux" : e2})
+
+    def test_it_does_not_contain_subtrees_that_are_not_in_the_instance(self):
+        error = ValidationError("a message", validator="foo", instance=[])
+        tree = ErrorTree([error])
+
+        with self.assertRaises(IndexError):
+            tree[0]
+
+    def test_if_its_in_the_tree_anyhow_it_does_not_raise_an_error(self):
+        """
+        If a validator is dumb (like :validator:`required` in draft 3) and
+        refers to a path that isn't in the instance, the tree still properly
+        returns a subtree for that path.
+
+        """
+
+        error = ValidationError(
+            "a message", validator="foo", instance={}, path=["foo"],
+        )
+        tree = ErrorTree([error])
+        self.assertIsInstance(tree["foo"], ErrorTree)
+
+
+class ValidatorTestMixin(object):
+    def setUp(self):
+        self.instance = mock.Mock()
+        self.schema = {}
+        self.resolver = mock.Mock()
+        self.validator = self.validator_class(self.schema)
+
+    def test_valid_instances_are_valid(self):
+        errors = iter([])
+
+        with mock.patch.object(
+            self.validator, "iter_errors", return_value=errors,
+        ):
+            self.assertTrue(
+                self.validator.is_valid(self.instance, self.schema)
+            )
+
+    def test_invalid_instances_are_not_valid(self):
+        errors = iter([mock.Mock()])
+
+        with mock.patch.object(
+            self.validator, "iter_errors", return_value=errors,
+        ):
+            self.assertFalse(
+                self.validator.is_valid(self.instance, self.schema)
+            )
+
+    def test_non_existent_properties_are_ignored(self):
+        instance, my_property, my_value = mock.Mock(), mock.Mock(), mock.Mock()
+        validate(instance=instance, schema={my_property : my_value})
+
+    def test_it_creates_a_ref_resolver_if_not_provided(self):
+        self.assertIsInstance(self.validator.resolver, RefResolver)
+
+    def test_it_delegates_to_a_ref_resolver(self):
+        resolver = RefResolver("", {})
+        schema = {"$ref" : mock.Mock()}
+
+        @contextlib.contextmanager
+        def resolving():
+            yield {"type": "integer"}
+
+        with mock.patch.object(resolver, "resolving") as resolve:
+            resolve.return_value = resolving()
+            with self.assertRaises(ValidationError):
+                self.validator_class(schema, resolver=resolver).validate(None)
+
+        resolve.assert_called_once_with(schema["$ref"])
+
+    def test_is_type_is_true_for_valid_type(self):
+        self.assertTrue(self.validator.is_type("foo", "string"))
+
+    def test_is_type_is_false_for_invalid_type(self):
+        self.assertFalse(self.validator.is_type("foo", "array"))
+
+    def test_is_type_evades_bool_inheriting_from_int(self):
+        self.assertFalse(self.validator.is_type(True, "integer"))
+        self.assertFalse(self.validator.is_type(True, "number"))
+
+    def test_is_type_raises_exception_for_unknown_type(self):
+        with self.assertRaises(UnknownType):
+            self.validator.is_type("foo", object())
+
+
+class TestDraft3Validator(ValidatorTestMixin, unittest.TestCase):
+    validator_class = Draft3Validator
+
+    def test_is_type_is_true_for_any_type(self):
+        self.assertTrue(self.validator.is_valid(mock.Mock(), {"type": "any"}))
+
+    def test_is_type_does_not_evade_bool_if_it_is_being_tested(self):
+        self.assertTrue(self.validator.is_type(True, "boolean"))
+        self.assertTrue(self.validator.is_valid(True, {"type": "any"}))
+
+
+class TestDraft4Validator(ValidatorTestMixin, unittest.TestCase):
+    validator_class = Draft4Validator
+
+
+class TestValidate(unittest.TestCase):
+    def test_draft3_validator_is_chosen(self):
+        schema = {"$schema" : "http://json-schema.org/draft-03/schema#"}
+        with mock.patch.object(Draft3Validator, "check_schema") as chk_schema:
+            validate({}, schema)
+            chk_schema.assert_called_once_with(schema)
+        # Make sure it works without the empty fragment
+        schema = {"$schema" : "http://json-schema.org/draft-03/schema"}
+        with mock.patch.object(Draft3Validator, "check_schema") as chk_schema:
+            validate({}, schema)
+            chk_schema.assert_called_once_with(schema)
+
+    def test_draft4_validator_is_chosen(self):
+        schema = {"$schema" : "http://json-schema.org/draft-04/schema#"}
+        with mock.patch.object(Draft4Validator, "check_schema") as chk_schema:
+            validate({}, schema)
+            chk_schema.assert_called_once_with(schema)
+
+    def test_draft4_validator_is_the_default(self):
+        with mock.patch.object(Draft4Validator, "check_schema") as chk_schema:
+            validate({}, {})
+            chk_schema.assert_called_once_with({})
+
+
+class TestValidatorMixin(unittest.TestCase):
+    def test_if_ref_is_present_then_the_schema_is_replaced(self):
+        class Validator(ValidatorMixin):
+            validate_ref = mock.Mock(return_value=[])
+            validate_type = mock.Mock(return_value=[])
+
+        Validator({"$ref" : "foo", "type" : "quux"}).validate(1)
+
+        self.assertTrue(Validator.validate_ref.called)
+        self.assertFalse(Validator.validate_type.called)
+
+
+class TestRefResolver(unittest.TestCase):
+
+    base_uri = ""
+    stored_uri = "foo://stored"
+    stored_schema = {"stored" : "schema"}
+
+    def setUp(self):
+        self.referrer = {}
+        self.store = {self.stored_uri : self.stored_schema}
+        self.resolver = RefResolver(self.base_uri, self.referrer, self.store)
+
+    def test_it_does_not_retrieve_schema_urls_from_the_network(self):
+        ref = Draft3Validator.META_SCHEMA["id"]
+        with mock.patch.object(self.resolver, "resolve_remote") as remote:
+            with self.resolver.resolving(ref) as resolved:
+                self.assertEqual(resolved, Draft3Validator.META_SCHEMA)
+        self.assertFalse(remote.called)
+
+    def test_it_resolves_local_refs(self):
+        ref = "#/properties/foo"
+        self.referrer["properties"] = {"foo" : object()}
+        with self.resolver.resolving(ref) as resolved:
+            self.assertEqual(resolved, self.referrer["properties"]["foo"])
+
+    def test_it_resolves_local_refs_with_id(self):
+        schema = {"id": "foo://bar/schema#", "a": {"foo": "bar"}}
+        resolver = RefResolver.from_schema(schema)
+        with resolver.resolving("#/a") as resolved:
+            self.assertEqual(resolved, schema["a"])
+        with resolver.resolving("foo://bar/schema#/a") as resolved:
+            self.assertEqual(resolved, schema["a"])
+
+    def test_it_retrieves_stored_refs(self):
+        with self.resolver.resolving(self.stored_uri) as resolved:
+            self.assertIs(resolved, self.stored_schema)
+
+        self.resolver.store["cached_ref"] = {"foo" : 12}
+        with self.resolver.resolving("cached_ref#/foo") as resolved:
+            self.assertEqual(resolved, 12)
+
+    def test_it_retrieves_unstored_refs_via_requests(self):
+        ref = "http://bar#baz"
+        schema = {"baz" : 12}
+
+        with mock.patch("jsonschema.validators.requests") as requests:
+            requests.get.return_value.json.return_value = schema
+            with self.resolver.resolving(ref) as resolved:
+                self.assertEqual(resolved, 12)
+        requests.get.assert_called_once_with("http://bar")
+
+    def test_it_retrieves_unstored_refs_via_urlopen(self):
+        ref = "http://bar#baz"
+        schema = {"baz" : 12}
+
+        with mock.patch("jsonschema.validators.requests", None):
+            with mock.patch("jsonschema.validators.urlopen") as urlopen:
+                urlopen.return_value.read.return_value = (
+                    json.dumps(schema).encode("utf8"))
+                with self.resolver.resolving(ref) as resolved:
+                    self.assertEqual(resolved, 12)
+        urlopen.assert_called_once_with("http://bar")
+
+    def test_it_can_construct_a_base_uri_from_a_schema(self):
+        schema = {"id" : "foo"}
+        resolver = RefResolver.from_schema(schema)
+        self.assertEqual(resolver.base_uri, "foo")
+        with resolver.resolving("") as resolved:
+            self.assertEqual(resolved, schema)
+        with resolver.resolving("#") as resolved:
+            self.assertEqual(resolved, schema)
+        with resolver.resolving("foo") as resolved:
+            self.assertEqual(resolved, schema)
+        with resolver.resolving("foo#") as resolved:
+            self.assertEqual(resolved, schema)
+
+    def test_it_can_construct_a_base_uri_from_a_schema_without_id(self):
+        schema = {}
+        resolver = RefResolver.from_schema(schema)
+        self.assertEqual(resolver.base_uri, "")
+        with resolver.resolving("") as resolved:
+            self.assertEqual(resolved, schema)
+        with resolver.resolving("#") as resolved:
+            self.assertEqual(resolved, schema)
+
+    def test_custom_uri_scheme_handlers(self):
+        schema = {"foo": "bar"}
+        ref = "foo://bar"
+        foo_handler = mock.Mock(return_value=schema)
+        resolver = RefResolver("", {}, handlers={"foo": foo_handler})
+        with resolver.resolving(ref) as resolved:
+            self.assertEqual(resolved, schema)
+        foo_handler.assert_called_once_with(ref)
+
+    def test_cache_remote_on(self):
+        ref = "foo://bar"
+        foo_handler = mock.Mock()
+        resolver = RefResolver(
+            "", {}, cache_remote=True, handlers={"foo" : foo_handler},
+        )
+        with resolver.resolving(ref):
+            pass
+        with resolver.resolving(ref):
+            pass
+        foo_handler.assert_called_once_with(ref)
+
+    def test_cache_remote_off(self):
+        ref = "foo://bar"
+        foo_handler = mock.Mock()
+        resolver = RefResolver(
+            "", {}, cache_remote=False, handlers={"foo" : foo_handler},
+        )
+        with resolver.resolving(ref):
+            pass
+        with resolver.resolving(ref):
+            pass
+        self.assertEqual(foo_handler.call_count, 2)
+
+    def test_if_you_give_it_junk_you_get_a_resolution_error(self):
+        ref = "foo://bar"
+        foo_handler = mock.Mock(side_effect=ValueError("Oh no! What's this?"))
+        resolver = RefResolver("", {}, handlers={"foo" : foo_handler})
+        with self.assertRaises(RefResolutionError) as err:
+            with resolver.resolving(ref):
+                pass
+        self.assertEqual(str(err.exception), "Oh no! What's this?")
+
+
+def sorted_errors(errors):
+    def key(error):
+        return (
+            [str(e) for e in error.path],
+            [str(e) for e in error.schema_path]
+        )
+    return sorted(errors, key=key)