skip uri test for pymongo < v2.9

docs/changelog.rst

@@ -4,7 +4,10 @@ Changelog
 
 Development
 ===========
-- (Fill this out as you fix issues and develop you features).
+- (Fill this out as you fix issues and develop your features).
+- Fixed using sets in field choices #1481
+- POTENTIAL BREAKING CHANGE: Fixed limit/skip/hint/batch_size chaining #1476
+- POTENTIAL BREAKING CHANGE: Changed a public `QuerySet.clone_into` method to a private `QuerySet._clone_into` #1476
 - Fixed connecting to a replica set with PyMongo 2.x #1436
 - Fixed an obscure error message when filtering by `field__in=non_iterable`. #1237
 

docs/guide/defining-documents.rst

@@ -150,7 +150,7 @@ arguments can be set on all fields:
     .. note:: If set, this field is also accessible through the `pk` field.
 
 :attr:`choices` (Default: None)
-    An iterable (e.g. a list or tuple) of choices to which the value of this
+    An iterable (e.g. list, tuple or set) of choices to which the value of this
     field should be limited.
 
     Can be either be a nested tuples of value (stored in mongo) and a
@@ -214,8 +214,8 @@ document class as the first argument::
 
 Dictionary Fields
 -----------------
-Often, an embedded document may be used instead of a dictionary – generally 
-embedded documents are recommended as dictionaries don’t support validation 
+Often, an embedded document may be used instead of a dictionary – generally
+embedded documents are recommended as dictionaries don’t support validation
 or custom field types. However, sometimes you will not know the structure of what you want to
 store; in this situation a :class:`~mongoengine.fields.DictField` is appropriate::
 

docs/upgrade.rst

@@ -2,6 +2,20 @@
 Upgrading
 #########
 
+Development
+***********
+(Fill this out whenever you introduce breaking changes to MongoEngine)
+
+This release includes various fixes for the `BaseQuerySet` methods and how they
+are chained together. Since version 0.10.1 applying limit/skip/hint/batch_size
+to an already-existing queryset wouldn't modify the underlying PyMongo cursor.
+This has been fixed now, so you'll need to make sure that your code didn't rely
+on the broken implementation.
+
+Additionally, a public `BaseQuerySet.clone_into` has been renamed to a private
+`_clone_into`. If you directly used that method in your code, you'll need to
+rename its occurrences.
+
 0.11.0
 ******
 This release includes a major rehaul of MongoEngine's code quality and

mongoengine/base/fields.py

@@ -193,7 +193,8 @@ class BaseField(object):
         EmbeddedDocument = _import_class('EmbeddedDocument')
 
         choice_list = self.choices
-        if isinstance(choice_list[0], (list, tuple)):
+        if isinstance(next(iter(choice_list)), (list, tuple)):
+            # next(iter) is useful for sets
             choice_list = [k for k, _ in choice_list]
 
         # Choices which are other types of Documents

mongoengine/connection.py

@@ -51,7 +51,9 @@ def register_connection(alias, name=None, host=None, port=None,
         MONGODB-CR (MongoDB Challenge Response protocol) for older servers.
     :param is_mock: explicitly use mongomock for this connection
         (can also be done by using `mongomock://` as db host prefix)
-    :param kwargs: allow ad-hoc parameters to be passed into the pymongo driver
+    :param kwargs: ad-hoc parameters to be passed into the pymongo driver,
+        for example maxpoolsize, tz_aware, etc. See the documentation
+        for pymongo's `MongoClient` for a full list.
 
     .. versionchanged:: 0.10.6 - added mongomock support
     """
@@ -241,9 +243,12 @@ def connect(db=None, alias=DEFAULT_CONNECTION_NAME, **kwargs):
     running on the default port on localhost. If authentication is needed,
     provide username and password arguments as well.
 
-    Multiple databases are supported by using aliases.  Provide a separate
+    Multiple databases are supported by using aliases. Provide a separate
     `alias` to connect to a different instance of :program:`mongod`.
 
+    See the docstring for `register_connection` for more details about all
+    supported kwargs.
+
     .. versionchanged:: 0.6 - added multiple database support.
     """
     if alias not in _connections:

mongoengine/fields.py

@@ -139,12 +139,12 @@ class URLField(StringField):
         # Check first if the scheme is valid
         scheme = value.split('://')[0].lower()
         if scheme not in self.schemes:
-            self.error('Invalid scheme {} in URL: {}'.format(scheme, value))
+            self.error(u'Invalid scheme {} in URL: {}'.format(scheme, value))
             return
 
         # Then check full URL
         if not self.url_regex.match(value):
-            self.error('Invalid URL: {}'.format(value))
+            self.error(u'Invalid URL: {}'.format(value))
             return
 
 

mongoengine/queryset/base.py

@@ -86,6 +86,7 @@ class BaseQuerySet(object):
         self._batch_size = None
         self.only_fields = []
         self._max_time_ms = None
+        self._comment = None
 
     def __call__(self, q_obj=None, class_check=True, read_preference=None,
                  **query):
@@ -706,39 +707,36 @@ class BaseQuerySet(object):
         with switch_db(self._document, alias) as cls:
             collection = cls._get_collection()
 
-        return self.clone_into(self.__class__(self._document, collection))
+        return self._clone_into(self.__class__(self._document, collection))
 
     def clone(self):
-        """Creates a copy of the current
-          :class:`~mongoengine.queryset.QuerySet`
+        """Create a copy of the current queryset."""
+        return self._clone_into(self.__class__(self._document, self._collection_obj))
 
-        .. versionadded:: 0.5
+    def _clone_into(self, new_qs):
+        """Copy all of the relevant properties of this queryset to
+        a new queryset (which has to be an instance of
+        :class:`~mongoengine.queryset.base.BaseQuerySet`).
         """
-        return self.clone_into(self.__class__(self._document, self._collection_obj))
-
-    def clone_into(self, cls):
-        """Creates a copy of the current
-          :class:`~mongoengine.queryset.base.BaseQuerySet` into another child class
-        """
-        if not isinstance(cls, BaseQuerySet):
+        if not isinstance(new_qs, BaseQuerySet):
             raise OperationError(
-                '%s is not a subclass of BaseQuerySet' % cls.__name__)
+                '%s is not a subclass of BaseQuerySet' % new_qs.__name__)
 
         copy_props = ('_mongo_query', '_initial_query', '_none', '_query_obj',
                       '_where_clause', '_loaded_fields', '_ordering', '_snapshot',
                       '_timeout', '_class_check', '_slave_okay', '_read_preference',
                       '_iter', '_scalar', '_as_pymongo', '_as_pymongo_coerce',
                       '_limit', '_skip', '_hint', '_auto_dereference',
-                      '_search_text', 'only_fields', '_max_time_ms')
+                      '_search_text', 'only_fields', '_max_time_ms', '_comment')
 
         for prop in copy_props:
             val = getattr(self, prop)
-            setattr(cls, prop, copy.copy(val))
+            setattr(new_qs, prop, copy.copy(val))
 
         if self._cursor_obj:
-            cls._cursor_obj = self._cursor_obj.clone()
+            new_qs._cursor_obj = self._cursor_obj.clone()
 
-        return cls
+        return new_qs
 
     def select_related(self, max_depth=1):
         """Handles dereferencing of :class:`~bson.dbref.DBRef` objects or
@@ -760,7 +758,11 @@ class BaseQuerySet(object):
         """
         queryset = self.clone()
         queryset._limit = n if n != 0 else 1
-        # Return self to allow chaining
+
+        # If a cursor object has already been created, apply the limit to it.
+        if queryset._cursor_obj:
+            queryset._cursor_obj.limit(queryset._limit)
+
         return queryset
 
     def skip(self, n):
@@ -771,6 +773,11 @@ class BaseQuerySet(object):
         """
         queryset = self.clone()
         queryset._skip = n
+
+        # If a cursor object has already been created, apply the skip to it.
+        if queryset._cursor_obj:
+            queryset._cursor_obj.skip(queryset._skip)
+
         return queryset
 
     def hint(self, index=None):
@@ -788,6 +795,11 @@ class BaseQuerySet(object):
         """
         queryset = self.clone()
         queryset._hint = index
+
+        # If a cursor object has already been created, apply the hint to it.
+        if queryset._cursor_obj:
+            queryset._cursor_obj.hint(queryset._hint)
+
         return queryset
 
     def batch_size(self, size):
@@ -801,6 +813,11 @@ class BaseQuerySet(object):
         """
         queryset = self.clone()
         queryset._batch_size = size
+
+        # If a cursor object has already been created, apply the batch size to it.
+        if queryset._cursor_obj:
+            queryset._cursor_obj.batch_size(queryset._batch_size)
+
         return queryset
 
     def distinct(self, field):
@@ -972,13 +989,31 @@ class BaseQuerySet(object):
     def order_by(self, *keys):
         """Order the :class:`~mongoengine.queryset.QuerySet` by the keys. The
         order may be specified by prepending each of the keys by a + or a -.
-        Ascending order is assumed.
+        Ascending order is assumed. If no keys are passed, existing ordering
+        is cleared instead.
 
         :param keys: fields to order the query results by; keys may be
             prefixed with **+** or **-** to determine the ordering direction
         """
         queryset = self.clone()
-        queryset._ordering = queryset._get_order_by(keys)
+
+        old_ordering = queryset._ordering
+        new_ordering = queryset._get_order_by(keys)
+
+        if queryset._cursor_obj:
+
+            # If a cursor object has already been created, apply the sort to it
+            if new_ordering:
+                queryset._cursor_obj.sort(new_ordering)
+
+            # If we're trying to clear a previous explicit ordering, we need
+            # to clear the cursor entirely (because PyMongo doesn't allow
+            # clearing an existing sort on a cursor).
+            elif old_ordering:
+                queryset._cursor_obj = None
+
+        queryset._ordering = new_ordering
+
         return queryset
 
     def comment(self, text):
@@ -1424,10 +1459,13 @@ class BaseQuerySet(object):
             raise StopIteration
 
         raw_doc = self._cursor.next()
+
         if self._as_pymongo:
             return self._get_as_pymongo(raw_doc)
-        doc = self._document._from_son(raw_doc,
-                                       _auto_dereference=self._auto_dereference, only_fields=self.only_fields)
+
+        doc = self._document._from_son(
+            raw_doc, _auto_dereference=self._auto_dereference,
+            only_fields=self.only_fields)
 
         if self._scalar:
             return self._get_scalar(doc)
@@ -1437,7 +1475,6 @@ class BaseQuerySet(object):
     def rewind(self):
         """Rewind the cursor to its unevaluated state.
 
-
         .. versionadded:: 0.3
         """
         self._iter = False
@@ -1487,43 +1524,54 @@ class BaseQuerySet(object):
 
     @property
     def _cursor(self):
-        if self._cursor_obj is None:
+        """Return a PyMongo cursor object corresponding to this queryset."""
 
-            # In PyMongo 3+, we define the read preference on a collection
-            # level, not a cursor level. Thus, we need to get a cloned
-            # collection object using `with_options` first.
-            if IS_PYMONGO_3 and self._read_preference is not None:
-                self._cursor_obj = self._collection\
-                    .with_options(read_preference=self._read_preference)\
-                    .find(self._query, **self._cursor_args)
-            else:
-                self._cursor_obj = self._collection.find(self._query,
-                                                         **self._cursor_args)
-            # Apply where clauses to cursor
-            if self._where_clause:
-                where_clause = self._sub_js_fields(self._where_clause)
-                self._cursor_obj.where(where_clause)
+        # If _cursor_obj already exists, return it immediately.
+        if self._cursor_obj is not None:
+            return self._cursor_obj
 
-            if self._ordering:
-                # Apply query ordering
-                self._cursor_obj.sort(self._ordering)
-            elif self._ordering is None and self._document._meta['ordering']:
-                # Otherwise, apply the ordering from the document model, unless
-                # it's been explicitly cleared via order_by with no arguments
-                order = self._get_order_by(self._document._meta['ordering'])
-                self._cursor_obj.sort(order)
+        # Create a new PyMongo cursor.
+        # XXX In PyMongo 3+, we define the read preference on a collection
+        # level, not a cursor level. Thus, we need to get a cloned collection
+        # object using `with_options` first.
+        if IS_PYMONGO_3 and self._read_preference is not None:
+            self._cursor_obj = self._collection\
+                .with_options(read_preference=self._read_preference)\
+                .find(self._query, **self._cursor_args)
+        else:
+            self._cursor_obj = self._collection.find(self._query,
+                                                     **self._cursor_args)
+        # Apply "where" clauses to cursor
+        if self._where_clause:
+            where_clause = self._sub_js_fields(self._where_clause)
+            self._cursor_obj.where(where_clause)
 
-            if self._limit is not None:
-                self._cursor_obj.limit(self._limit)
+        # Apply ordering to the cursor.
+        # XXX self._ordering can be equal to:
+        # * None if we didn't explicitly call order_by on this queryset.
+        # * A list of PyMongo-style sorting tuples.
+        # * An empty list if we explicitly called order_by() without any
+        #   arguments. This indicates that we want to clear the default
+        #   ordering.
+        if self._ordering:
+            # explicit ordering
+            self._cursor_obj.sort(self._ordering)
+        elif self._ordering is None and self._document._meta['ordering']:
+            # default ordering
+            order = self._get_order_by(self._document._meta['ordering'])
+            self._cursor_obj.sort(order)
 
-            if self._skip is not None:
-                self._cursor_obj.skip(self._skip)
+        if self._limit is not None:
+            self._cursor_obj.limit(self._limit)
 
-            if self._hint != -1:
-                self._cursor_obj.hint(self._hint)
+        if self._skip is not None:
+            self._cursor_obj.skip(self._skip)
 
-            if self._batch_size is not None:
-                self._cursor_obj.batch_size(self._batch_size)
+        if self._hint != -1:
+            self._cursor_obj.hint(self._hint)
+
+        if self._batch_size is not None:
+            self._cursor_obj.batch_size(self._batch_size)
 
         return self._cursor_obj
 
@@ -1698,7 +1746,13 @@ class BaseQuerySet(object):
         return ret
 
     def _get_order_by(self, keys):
-        """Creates a list of order by fields"""
+        """Given a list of MongoEngine-style sort keys, return a list
+        of sorting tuples that can be applied to a PyMongo cursor. For
+        example:
+
+        >>> qs._get_order_by(['-last_name', 'first_name'])
+        [('last_name', -1), ('first_name', 1)]
+        """
         key_list = []
         for key in keys:
             if not key:
@@ -1711,17 +1765,19 @@ class BaseQuerySet(object):
             direction = pymongo.ASCENDING
             if key[0] == '-':
                 direction = pymongo.DESCENDING
+
             if key[0] in ('-', '+'):
                 key = key[1:]
+
             key = key.replace('__', '.')
             try:
                 key = self._document._translate_field_name(key)
             except Exception:
+                # TODO this exception should be more specific
                 pass
+
             key_list.append((key, direction))
 
-        if self._cursor_obj and key_list:
-            self._cursor_obj.sort(key_list)
         return key_list
 
     def _get_scalar(self, doc):
@@ -1819,10 +1875,21 @@ class BaseQuerySet(object):
         return code
 
     def _chainable_method(self, method_name, val):
+        """Call a particular method on the PyMongo cursor call a particular chainable method
+        with the provided value.
+        """
         queryset = self.clone()
-        method = getattr(queryset._cursor, method_name)
-        method(val)
+
+        # Get an existing cursor object or create a new one
+        cursor = queryset._cursor
+
+        # Find the requested method on the cursor and call it with the
+        # provided value
+        getattr(cursor, method_name)(val)
+
+        # Cache the value on the queryset._{method_name}
         setattr(queryset, '_' + method_name, val)
+
         return queryset
 
     # Deprecated

mongoengine/queryset/queryset.py

@@ -136,13 +136,15 @@ class QuerySet(BaseQuerySet):
         return self._len
 
     def no_cache(self):
-        """Convert to a non_caching queryset
+        """Convert to a non-caching queryset
 
         .. versionadded:: 0.8.3 Convert to non caching queryset
         """
         if self._result_cache is not None:
             raise OperationError('QuerySet already cached')
-        return self.clone_into(QuerySetNoCache(self._document, self._collection))
+
+        return self._clone_into(QuerySetNoCache(self._document,
+                                                self._collection))
 
 
 class QuerySetNoCache(BaseQuerySet):
@@ -153,7 +155,7 @@ class QuerySetNoCache(BaseQuerySet):
 
         .. versionadded:: 0.8.3 Convert to caching queryset
         """
-        return self.clone_into(QuerySet(self._document, self._collection))
+        return self._clone_into(QuerySet(self._document, self._collection))
 
     def __repr__(self):
         """Provides the string representation of the QuerySet

tests/fields/fields.py

@@ -1,13 +1,12 @@
 # -*- coding: utf-8 -*-
-import six
-from nose.plugins.skip import SkipTest
-
 import datetime
 import unittest
 import uuid
 import math
 import itertools
 import re
+
+from nose.plugins.skip import SkipTest
 import six
 
 try:
@@ -27,21 +26,13 @@ from mongoengine import *
 from mongoengine.connection import get_db
 from mongoengine.base import (BaseDict, BaseField, EmbeddedDocumentList,
                               _document_registry)
-from mongoengine.errors import NotRegistered, DoesNotExist
+
+from tests.utils import MongoDBTestCase
 
 __all__ = ("FieldTest", "EmbeddedDocumentListFieldTestCase")
 
 
-class FieldTest(unittest.TestCase):
-
-    def setUp(self):
-        connect(db='mongoenginetest')
-        self.db = get_db()
-
-    def tearDown(self):
-        self.db.drop_collection('fs.files')
-        self.db.drop_collection('fs.chunks')
-        self.db.drop_collection('mongoengine.counters')
+class FieldTest(MongoDBTestCase):
 
     def test_default_values_nothing_set(self):
         """Ensure that default field values are used when creating a document.
@@ -227,9 +218,9 @@ class FieldTest(unittest.TestCase):
         self.assertTrue(isinstance(ret.comp_dt_fld, datetime.datetime))
 
     def test_not_required_handles_none_from_database(self):
-        """Ensure that every fields can handle null values from the database.
+        """Ensure that every field can handle null values from the
+        database.
         """
-
         class HandleNoneFields(Document):
             str_fld = StringField(required=True)
             int_fld = IntField(required=True)
@@ -350,11 +341,12 @@ class FieldTest(unittest.TestCase):
         person.validate()
 
     def test_url_validation(self):
-        """Ensure that URLFields validate urls properly.
-        """
+        """Ensure that URLFields validate urls properly."""
         class Link(Document):
             url = URLField()
 
+        Link.drop_collection()
+
         link = Link()
         link.url = 'google'
         self.assertRaises(ValidationError, link.validate)
@@ -362,6 +354,27 @@ class FieldTest(unittest.TestCase):
         link.url = 'http://www.google.com:8080'
         link.validate()
 
+    def test_unicode_url_validation(self):
+        """Ensure unicode URLs are validated properly."""
+        class Link(Document):
+            url = URLField()
+
+        Link.drop_collection()
+
+        link = Link()
+        link.url = u'http://привет.com'
+
+        # TODO fix URL validation - this *IS* a valid URL
+        # For now we just want to make sure that the error message is correct
+        try:
+            link.validate()
+            self.assertTrue(False)
+        except ValidationError as e:
+            self.assertEqual(
+                unicode(e),
+                u"ValidationError (Link:None) (Invalid URL: http://\u043f\u0440\u0438\u0432\u0435\u0442.com: ['url'])"
+            )
+
     def test_url_scheme_validation(self):
         """Ensure that URLFields validate urls with specific schemes properly.
         """
@@ -3186,26 +3199,42 @@ class FieldTest(unittest.TestCase):
         att.delete()
         self.assertEqual(0, Attachment.objects.count())
 
-    def test_choices_validation(self):
-        """Ensure that value is in a container of allowed values.
+    def test_choices_allow_using_sets_as_choices(self):
+        """Ensure that sets can be used when setting choices
         """
         class Shirt(Document):
-            size = StringField(max_length=3, choices=(
-                ('S', 'Small'), ('M', 'Medium'), ('L', 'Large'),
-                ('XL', 'Extra Large'), ('XXL', 'Extra Extra Large')))
+            size = StringField(choices={'M', 'L'})
 
-        Shirt.drop_collection()
+        Shirt(size='M').validate()
+
+    def test_choices_validation_allow_no_value(self):
+        """Ensure that .validate passes and no value was provided
+        for a field setup with choices
+        """
+        class Shirt(Document):
+            size = StringField(choices=('S', 'M'))
 
         shirt = Shirt()
         shirt.validate()
 
-        shirt.size = "S"
+    def test_choices_validation_accept_possible_value(self):
+        """Ensure that value is in a container of allowed values.
+        """
+        class Shirt(Document):
+            size = StringField(choices=('S', 'M'))
+
+        shirt = Shirt(size='S')
         shirt.validate()
 
-        shirt.size = "XS"
-        self.assertRaises(ValidationError, shirt.validate)
+    def test_choices_validation_reject_unknown_value(self):
+        """Ensure that unallowed value are rejected upon validation
+        """
+        class Shirt(Document):
+            size = StringField(choices=('S', 'M'))
 
-        Shirt.drop_collection()
+        shirt = Shirt(size="XS")
+        with self.assertRaises(ValidationError):
+            shirt.validate()
 
     def test_choices_validation_documents(self):
         """
@@ -4024,12 +4053,13 @@ class FieldTest(unittest.TestCase):
         self.assertTrue(isinstance(doc.some_long, six.integer_types))
 
 
-class EmbeddedDocumentListFieldTestCase(unittest.TestCase):
-
-    @classmethod
-    def setUpClass(cls):
-        cls.db = connect(db='EmbeddedDocumentListFieldTestCase')
+class EmbeddedDocumentListFieldTestCase(MongoDBTestCase):
 
+    def setUp(self):
+        """
+        Create two BlogPost entries in the database, each with
+        several EmbeddedDocuments.
+        """
         class Comments(EmbeddedDocument):
             author = StringField()
             message = StringField()
@@ -4037,14 +4067,11 @@ class EmbeddedDocumentListFieldTestCase(unittest.TestCase):
         class BlogPost(Document):
             comments = EmbeddedDocumentListField(Comments)
 
-        cls.Comments = Comments
-        cls.BlogPost = BlogPost
+        BlogPost.drop_collection()
+
+        self.Comments = Comments
+        self.BlogPost = BlogPost
 
-    def setUp(self):
-        """
-        Create two BlogPost entries in the database, each with
-        several EmbeddedDocuments.
-        """
         self.post1 = self.BlogPost(comments=[
             self.Comments(author='user1', message='message1'),
             self.Comments(author='user2', message='message1')
@@ -4056,13 +4083,6 @@ class EmbeddedDocumentListFieldTestCase(unittest.TestCase):
             self.Comments(author='user3', message='message1')
         ]).save()
 
-    def tearDown(self):
-        self.BlogPost.drop_collection()
-
-    @classmethod
-    def tearDownClass(cls):
-        cls.db.drop_database('EmbeddedDocumentListFieldTestCase')
-
     def test_no_keyword_filter(self):
         """
         Tests the filter method of a List of Embedded Documents
@@ -4420,7 +4440,8 @@ class EmbeddedDocumentListFieldTestCase(unittest.TestCase):
             my_list = ListField(EmbeddedDocumentField(EmbeddedWithUnique))
 
         A(my_list=[]).save()
-        self.assertRaises(NotUniqueError, lambda: A(my_list=[]).save())
+        with self.assertRaises(NotUniqueError):
+            A(my_list=[]).save()
 
         class EmbeddedWithSparseUnique(EmbeddedDocument):
             number = IntField(unique=True, sparse=True)
@@ -4428,6 +4449,9 @@ class EmbeddedDocumentListFieldTestCase(unittest.TestCase):
         class B(Document):
             my_list = ListField(EmbeddedDocumentField(EmbeddedWithSparseUnique))
 
+        A.drop_collection()
+        B.drop_collection()
+
         B(my_list=[]).save()
         B(my_list=[]).save()
 
@@ -4467,6 +4491,8 @@ class EmbeddedDocumentListFieldTestCase(unittest.TestCase):
             a_field = IntField()
             c_field = IntField(custom_data=custom_data)
 
+        CustomData.drop_collection()
+
         a1 = CustomData(a_field=1, c_field=2).save()
         self.assertEqual(2, a1.c_field)
         self.assertFalse(hasattr(a1.c_field, 'custom_data'))

tests/fields/file_tests.py

@@ -18,15 +18,13 @@ try:
 except ImportError:
     HAS_PIL = False
 
+from tests.utils import MongoDBTestCase
+
 TEST_IMAGE_PATH = os.path.join(os.path.dirname(__file__), 'mongoengine.png')
 TEST_IMAGE2_PATH = os.path.join(os.path.dirname(__file__), 'mongodb_leaf.png')
 
 
-class FileTest(unittest.TestCase):
-
-    def setUp(self):
-        connect(db='mongoenginetest')
-        self.db = get_db()
+class FileTest(MongoDBTestCase):
 
     def tearDown(self):
         self.db.drop_collection('fs.files')

tests/queryset/queryset.py

@@ -106,58 +106,111 @@ class QuerySetTest(unittest.TestCase):
             list(BlogPost.objects(author2__name="test"))
 
     def test_find(self):
-        """Ensure that a query returns a valid set of results.
-        """
-        self.Person(name="User A", age=20).save()
-        self.Person(name="User B", age=30).save()
+        """Ensure that a query returns a valid set of results."""
+        user_a = self.Person.objects.create(name='User A', age=20)
+        user_b = self.Person.objects.create(name='User B', age=30)
 
         # Find all people in the collection
         people = self.Person.objects
         self.assertEqual(people.count(), 2)
         results = list(people)
+
         self.assertTrue(isinstance(results[0], self.Person))
         self.assertTrue(isinstance(results[0].id, (ObjectId, str, unicode)))
-        self.assertEqual(results[0].name, "User A")
+
+        self.assertEqual(results[0], user_a)
+        self.assertEqual(results[0].name, 'User A')
         self.assertEqual(results[0].age, 20)
-        self.assertEqual(results[1].name, "User B")
+
+        self.assertEqual(results[1], user_b)
+        self.assertEqual(results[1].name, 'User B')
         self.assertEqual(results[1].age, 30)
 
-        # Use a query to filter the people found to just person1
+        # Filter people by age
         people = self.Person.objects(age=20)
         self.assertEqual(people.count(), 1)
         person = people.next()
+        self.assertEqual(person, user_a)
         self.assertEqual(person.name, "User A")
         self.assertEqual(person.age, 20)
 
-        # Test limit
+    def test_limit(self):
+        """Ensure that QuerySet.limit works as expected."""
+        user_a = self.Person.objects.create(name='User A', age=20)
+        user_b = self.Person.objects.create(name='User B', age=30)
+
+        # Test limit on a new queryset
         people = list(self.Person.objects.limit(1))
         self.assertEqual(len(people), 1)
-        self.assertEqual(people[0].name, 'User A')
+        self.assertEqual(people[0], user_a)
 
-        # Test skip
+        # Test limit on an existing queryset
+        people = self.Person.objects
+        self.assertEqual(len(people), 2)
+        people2 = people.limit(1)
+        self.assertEqual(len(people), 2)
+        self.assertEqual(len(people2), 1)
+        self.assertEqual(people2[0], user_a)
+
+        # Test chaining of only after limit
+        person = self.Person.objects().limit(1).only('name').first()
+        self.assertEqual(person, user_a)
+        self.assertEqual(person.name, 'User A')
+        self.assertEqual(person.age, None)
+
+    def test_skip(self):
+        """Ensure that QuerySet.skip works as expected."""
+        user_a = self.Person.objects.create(name='User A', age=20)
+        user_b = self.Person.objects.create(name='User B', age=30)
+
+        # Test skip on a new queryset
         people = list(self.Person.objects.skip(1))
         self.assertEqual(len(people), 1)
-        self.assertEqual(people[0].name, 'User B')
+        self.assertEqual(people[0], user_b)
 
-        person3 = self.Person(name="User C", age=40)
-        person3.save()
+        # Test skip on an existing queryset
+        people = self.Person.objects
+        self.assertEqual(len(people), 2)
+        people2 = people.skip(1)
+        self.assertEqual(len(people), 2)
+        self.assertEqual(len(people2), 1)
+        self.assertEqual(people2[0], user_b)
+
+        # Test chaining of only after skip
+        person = self.Person.objects().skip(1).only('name').first()
+        self.assertEqual(person, user_b)
+        self.assertEqual(person.name, 'User B')
+        self.assertEqual(person.age, None)
+
+    def test_slice(self):
+        """Ensure slicing a queryset works as expected."""
+        user_a = self.Person.objects.create(name='User A', age=20)
+        user_b = self.Person.objects.create(name='User B', age=30)
+        user_c = self.Person.objects.create(name="User C", age=40)
 
         # Test slice limit
         people = list(self.Person.objects[:2])
         self.assertEqual(len(people), 2)
-        self.assertEqual(people[0].name, 'User A')
-        self.assertEqual(people[1].name, 'User B')
+        self.assertEqual(people[0], user_a)
+        self.assertEqual(people[1], user_b)
 
         # Test slice skip
         people = list(self.Person.objects[1:])
         self.assertEqual(len(people), 2)
-        self.assertEqual(people[0].name, 'User B')
-        self.assertEqual(people[1].name, 'User C')
+        self.assertEqual(people[0], user_b)
+        self.assertEqual(people[1], user_c)
 
         # Test slice limit and skip
         people = list(self.Person.objects[1:2])
         self.assertEqual(len(people), 1)
-        self.assertEqual(people[0].name, 'User B')
+        self.assertEqual(people[0], user_b)
+
+        # Test slice limit and skip on an existing queryset
+        people = self.Person.objects
+        self.assertEqual(len(people), 3)
+        people2 = people[1:2]
+        self.assertEqual(len(people2), 1)
+        self.assertEqual(people2[0], user_b)
 
         # Test slice limit and skip cursor reset
         qs = self.Person.objects[1:2]
@@ -168,6 +221,7 @@ class QuerySetTest(unittest.TestCase):
         self.assertEqual(len(people), 1)
         self.assertEqual(people[0].name, 'User B')
 
+        # Test empty slice
         people = list(self.Person.objects[1:1])
         self.assertEqual(len(people), 0)
 
@@ -187,12 +241,6 @@ class QuerySetTest(unittest.TestCase):
         self.assertEqual("[<Person: Person object>, <Person: Person object>]",
                          "%s" % self.Person.objects[51:53])
 
-        # Test only after limit
-        self.assertEqual(self.Person.objects().limit(2).only('name')[0].age, None)
-
-        # Test only after skip
-        self.assertEqual(self.Person.objects().skip(2).only('name')[0].age, None)
-
     def test_find_one(self):
         """Ensure that a query using find_one returns a valid result.
         """
@@ -1226,6 +1274,7 @@ class QuerySetTest(unittest.TestCase):
 
         BlogPost.drop_collection()
 
+        # default ordering should be used by default
         with db_ops_tracker() as q:
             BlogPost.objects.filter(title='whatever').first()
             self.assertEqual(len(q.get_ops()), 1)
@@ -1234,11 +1283,28 @@ class QuerySetTest(unittest.TestCase):
                 {'published_date': -1}
             )
 
+        # calling order_by() should clear the default ordering
         with db_ops_tracker() as q:
             BlogPost.objects.filter(title='whatever').order_by().first()
             self.assertEqual(len(q.get_ops()), 1)
             self.assertFalse('$orderby' in q.get_ops()[0]['query'])
 
+        # calling an explicit order_by should use a specified sort
+        with db_ops_tracker() as q:
+            BlogPost.objects.filter(title='whatever').order_by('published_date').first()
+            self.assertEqual(len(q.get_ops()), 1)
+            self.assertEqual(
+                q.get_ops()[0]['query']['$orderby'],
+                {'published_date': 1}
+            )
+
+        # calling order_by() after an explicit sort should clear it
+        with db_ops_tracker() as q:
+            qs = BlogPost.objects.filter(title='whatever').order_by('published_date')
+            qs.order_by().first()
+            self.assertEqual(len(q.get_ops()), 1)
+            self.assertFalse('$orderby' in q.get_ops()[0]['query'])
+
     def test_no_ordering_for_get(self):
         """ Ensure that Doc.objects.get doesn't use any ordering.
         """

tests/test_connection.py

@@ -285,8 +285,7 @@ class ConnectionTest(unittest.TestCase):
         self.assertTrue(isinstance(conn, pymongo.mongo_client.MongoClient))
 
     def test_connection_kwargs(self):
-        """Ensure that connection kwargs get passed to pymongo.
-        """
+        """Ensure that connection kwargs get passed to pymongo."""
         connect('mongoenginetest', alias='t1', tz_aware=True)
         conn = get_connection('t1')
 
@@ -296,6 +295,32 @@ class ConnectionTest(unittest.TestCase):
         conn = get_connection('t2')
         self.assertFalse(get_tz_awareness(conn))
 
+    def test_connection_pool_via_kwarg(self):
+        """Ensure we can specify a max connection pool size using
+        a connection kwarg.
+        """
+        # Use "max_pool_size" or "maxpoolsize" depending on PyMongo version
+        # (former was changed to the latter as described in
+        # https://jira.mongodb.org/browse/PYTHON-854).
+        # TODO remove once PyMongo < 3.0 support is dropped
+        if pymongo.version_tuple[0] >= 3:
+            pool_size_kwargs = {'maxpoolsize': 100}
+        else:
+            pool_size_kwargs = {'max_pool_size': 100}
+
+        conn = connect('mongoenginetest', alias='max_pool_size_via_kwarg', **pool_size_kwargs)
+        self.assertEqual(conn.max_pool_size, 100)
+
+    def test_connection_pool_via_uri(self):
+        """Ensure we can specify a max connection pool size using
+        an option in a connection URI.
+        """
+        if pymongo.version_tuple[0] == 2 and pymongo.version_tuple[1] < 9:
+            raise SkipTest('maxpoolsize as a URI option is only supported in PyMongo v2.9+')
+
+        conn = connect(host='mongodb://localhost/test?maxpoolsize=100', alias='max_pool_size_via_uri')
+        self.assertEqual(conn.max_pool_size, 100)
+
     def test_write_concern(self):
         """Ensure write concern can be specified in connect() via
         a kwarg or as part of the connection URI.

tests/utils.py

@@ -0,0 +1,22 @@
+import unittest
+
+from mongoengine import connect
+from mongoengine.connection import get_db
+
+MONGO_TEST_DB = 'mongoenginetest'
+
+
+class MongoDBTestCase(unittest.TestCase):
+    """Base class for tests that need a mongodb connection
+    db is being dropped automatically
+    """
+
+    @classmethod
+    def setUpClass(cls):
+        cls._connection = connect(db=MONGO_TEST_DB)
+        cls._connection.drop_database(MONGO_TEST_DB)
+        cls.db = get_db()
+
+    @classmethod
+    def tearDownClass(cls):
+        cls._connection.drop_database(MONGO_TEST_DB)