diff --git a/mongoengine/connection.py b/mongoengine/connection.py
index 38ebb243..c0cfde31 100644
--- a/mongoengine/connection.py
+++ b/mongoengine/connection.py
@@ -1,10 +1,10 @@
 from pymongo import MongoClient, ReadPreference, uri_parser
 import six
 
-from mongoengine.python_support import IS_PYMONGO_3
+from mongoengine.pymongo_support import IS_PYMONGO_3
 
 __all__ = ['MongoEngineConnectionError', 'connect', 'register_connection',
-           'DEFAULT_CONNECTION_NAME']
+           'DEFAULT_CONNECTION_NAME', 'get_db']
 
 
 DEFAULT_CONNECTION_NAME = 'default'
diff --git a/mongoengine/context_managers.py b/mongoengine/context_managers.py
index d1e5d9ef..98bd897b 100644
--- a/mongoengine/context_managers.py
+++ b/mongoengine/context_managers.py
@@ -5,6 +5,7 @@ from six import iteritems
 
 from mongoengine.common import _import_class
 from mongoengine.connection import DEFAULT_CONNECTION_NAME, get_db
+from mongoengine.pymongo_support import count_documents
 
 __all__ = ('switch_db', 'switch_collection', 'no_dereference',
            'no_sub_classes', 'query_counter', 'set_write_concern')
@@ -237,7 +238,7 @@ class query_counter(object):
         and substracting the queries issued by this context. In fact everytime this is called, 1 query is
         issued so we need to balance that
         """
-        count = self.db.system.profile.find(self._ignored_query).count() - self._ctx_query_counter
+        count = count_documents(self.db.system.profile, self._ignored_query) - self._ctx_query_counter
         self._ctx_query_counter += 1    # Account for the query we just issued to gather the information
         return count
 
diff --git a/mongoengine/document.py b/mongoengine/document.py
index 84c1d699..5981d8d1 100644
--- a/mongoengine/document.py
+++ b/mongoengine/document.py
@@ -18,7 +18,7 @@ from mongoengine.context_managers import (set_write_concern,
                                           switch_db)
 from mongoengine.errors import (InvalidDocumentError, InvalidQueryError,
                                 SaveConditionError)
-from mongoengine.python_support import IS_PYMONGO_3
+from mongoengine.pymongo_support import IS_PYMONGO_3, list_collection_names
 from mongoengine.queryset import (NotUniqueError, OperationError,
                                   QuerySet, transform)
 
@@ -228,7 +228,7 @@ class Document(six.with_metaclass(TopLevelDocumentMetaclass, BaseDocument)):
 
         # If the collection already exists and has different options
         # (i.e. isn't capped or has different max/size), raise an error.
-        if collection_name in db.collection_names():
+        if collection_name in list_collection_names(db, include_system_collections=True):
             collection = db[collection_name]
             options = collection.options()
             if (
diff --git a/mongoengine/pymongo_support.py b/mongoengine/pymongo_support.py
new file mode 100644
index 00000000..0d607162
--- /dev/null
+++ b/mongoengine/pymongo_support.py
@@ -0,0 +1,33 @@
+"""
+Helper functions, constants, and types to aid with PyMongo v2.7 - v3.x support.
+"""
+import pymongo
+
+_PYMONGO_37 = (3, 7)
+
+PYMONGO_VERSION = tuple(pymongo.version_tuple[:2])
+
+IS_PYMONGO_3 = PYMONGO_VERSION[0] >= 3
+IS_PYMONGO_GTE_37 = PYMONGO_VERSION >= _PYMONGO_37
+
+
+def count_documents(collection, filter):
+    """Pymongo>3.7 deprecates count in favour of count_documents"""
+    if IS_PYMONGO_GTE_37:
+        return collection.count_documents(filter)
+    else:
+        count = collection.find(filter).count()
+    return count
+
+
+def list_collection_names(db, include_system_collections=False):
+    """Pymongo>3.7 deprecates collection_names in favour of list_collection_names"""
+    if IS_PYMONGO_GTE_37:
+        collections = db.list_collection_names()
+    else:
+        collections = db.collection_names()
+
+    if not include_system_collections:
+        collections = [c for c in collections if not c.startswith('system.')]
+
+    return collections
diff --git a/mongoengine/python_support.py b/mongoengine/python_support.py
index 7e8e108f..57e467db 100644
--- a/mongoengine/python_support.py
+++ b/mongoengine/python_support.py
@@ -1,13 +1,8 @@
 """
-Helper functions, constants, and types to aid with Python v2.7 - v3.x and
-PyMongo v2.7 - v3.x support.
+Helper functions, constants, and types to aid with Python v2.7 - v3.x support
 """
-import pymongo
 import six
 
-
-IS_PYMONGO_3 = pymongo.version_tuple[0] >= 3
-
 # six.BytesIO resolves to StringIO.StringIO in Py2 and io.BytesIO in Py3.
 StringIO = six.BytesIO
 
diff --git a/mongoengine/queryset/base.py b/mongoengine/queryset/base.py
index 8c22c5b9..9ddfeab2 100644
--- a/mongoengine/queryset/base.py
+++ b/mongoengine/queryset/base.py
@@ -21,7 +21,7 @@ from mongoengine.connection import get_db
 from mongoengine.context_managers import set_write_concern, switch_db
 from mongoengine.errors import (InvalidQueryError, LookUpError,
                                 NotUniqueError, OperationError)
-from mongoengine.python_support import IS_PYMONGO_3
+from mongoengine.pymongo_support import IS_PYMONGO_3
 from mongoengine.queryset import transform
 from mongoengine.queryset.field_list import QueryFieldList
 from mongoengine.queryset.visitor import Q, QNode
diff --git a/mongoengine/queryset/transform.py b/mongoengine/queryset/transform.py
index c00271f3..3de10a69 100644
--- a/mongoengine/queryset/transform.py
+++ b/mongoengine/queryset/transform.py
@@ -10,7 +10,7 @@ from mongoengine.base import UPDATE_OPERATORS
 from mongoengine.common import _import_class
 from mongoengine.connection import get_connection
 from mongoengine.errors import InvalidQueryError
-from mongoengine.python_support import IS_PYMONGO_3
+from mongoengine.pymongo_support import IS_PYMONGO_3
 
 __all__ = ('query', 'update')
 
diff --git a/tests/document/class_methods.py b/tests/document/class_methods.py
index 88937ec8..421618e4 100644
--- a/tests/document/class_methods.py
+++ b/tests/document/class_methods.py
@@ -2,6 +2,7 @@
 import unittest
 
 from mongoengine import *
+from mongoengine.pymongo_support import list_collection_names
 
 from mongoengine.queryset import NULLIFY, PULL
 from mongoengine.connection import get_db
@@ -27,9 +28,7 @@ class ClassMethodsTest(unittest.TestCase):
         self.Person = Person
 
     def tearDown(self):
-        for collection in self.db.collection_names():
-            if 'system.' in collection:
-                continue
+        for collection in list_collection_names(self.db):
             self.db.drop_collection(collection)
 
     def test_definition(self):
@@ -66,10 +65,10 @@ class ClassMethodsTest(unittest.TestCase):
         """
         collection_name = 'person'
         self.Person(name='Test').save()
-        self.assertIn(collection_name, self.db.collection_names())
+        self.assertIn(collection_name, list_collection_names(self.db))
 
         self.Person.drop_collection()
-        self.assertNotIn(collection_name, self.db.collection_names())
+        self.assertNotIn(collection_name, list_collection_names(self.db))
 
     def test_register_delete_rule(self):
         """Ensure that register delete rule adds a delete rule to the document
@@ -340,7 +339,7 @@ class ClassMethodsTest(unittest.TestCase):
             meta = {'collection': collection_name}
 
         Person(name="Test User").save()
-        self.assertIn(collection_name, self.db.collection_names())
+        self.assertIn(collection_name, list_collection_names(self.db))
 
         user_obj = self.db[collection_name].find_one()
         self.assertEqual(user_obj['name'], "Test User")
@@ -349,7 +348,7 @@ class ClassMethodsTest(unittest.TestCase):
         self.assertEqual(user_obj.name, "Test User")
 
         Person.drop_collection()
-        self.assertNotIn(collection_name, self.db.collection_names())
+        self.assertNotIn(collection_name, list_collection_names(self.db))
 
     def test_collection_name_and_primary(self):
         """Ensure that a collection with a specified name may be used.
diff --git a/tests/document/delta.py b/tests/document/delta.py
index 942e3a0a..504c1707 100644
--- a/tests/document/delta.py
+++ b/tests/document/delta.py
@@ -3,16 +3,14 @@ import unittest
 
 from bson import SON
 from mongoengine import *
-from mongoengine.connection import get_db
-
-__all__ = ("DeltaTest",)
+from mongoengine.pymongo_support import list_collection_names
+from tests.utils import MongoDBTestCase
 
 
-class DeltaTest(unittest.TestCase):
+class DeltaTest(MongoDBTestCase):
 
     def setUp(self):
-        connect(db='mongoenginetest')
-        self.db = get_db()
+        super(DeltaTest, self).setUp()
 
         class Person(Document):
             name = StringField()
@@ -25,9 +23,7 @@ class DeltaTest(unittest.TestCase):
         self.Person = Person
 
     def tearDown(self):
-        for collection in self.db.collection_names():
-            if 'system.' in collection:
-                continue
+        for collection in list_collection_names(self.db):
             self.db.drop_collection(collection)
 
     def test_delta(self):
diff --git a/tests/document/inheritance.py b/tests/document/inheritance.py
index 83c2a80a..d81039f4 100644
--- a/tests/document/inheritance.py
+++ b/tests/document/inheritance.py
@@ -6,23 +6,18 @@ from six import iteritems
 
 from mongoengine import (BooleanField, Document, EmbeddedDocument,
                          EmbeddedDocumentField, GenericReferenceField,
-                         IntField, ReferenceField, StringField, connect)
-from mongoengine.connection import get_db
+                         IntField, ReferenceField, StringField)
+from mongoengine.pymongo_support import list_collection_names
+from tests.utils import MongoDBTestCase
 from tests.fixtures import Base
 
 __all__ = ('InheritanceTest', )
 
 
-class InheritanceTest(unittest.TestCase):
-
-    def setUp(self):
-        connect(db='mongoenginetest')
-        self.db = get_db()
+class InheritanceTest(MongoDBTestCase):
 
     def tearDown(self):
-        for collection in self.db.collection_names():
-            if 'system.' in collection:
-                continue
+        for collection in list_collection_names(self.db):
             self.db.drop_collection(collection)
 
     def test_constructor_cls(self):
diff --git a/tests/document/instance.py b/tests/document/instance.py
index 051eda68..9b28f1b4 100644
--- a/tests/document/instance.py
+++ b/tests/document/instance.py
@@ -12,6 +12,7 @@ from bson import DBRef, ObjectId
 from pymongo.errors import DuplicateKeyError
 from six import iteritems
 
+from mongoengine.pymongo_support import list_collection_names
 from tests import fixtures
 from tests.fixtures import (PickleEmbedded, PickleTest, PickleSignalsTest,
                             PickleDynamicEmbedded, PickleDynamicTest)
@@ -55,9 +56,7 @@ class InstanceTest(MongoDBTestCase):
         self.Job = Job
 
     def tearDown(self):
-        for collection in self.db.collection_names():
-            if 'system.' in collection:
-                continue
+        for collection in list_collection_names(self.db):
             self.db.drop_collection(collection)
 
     def assertDbEqual(self, docs):
@@ -572,7 +571,7 @@ class InstanceTest(MongoDBTestCase):
 
         Post.drop_collection()
 
-        Post._get_collection().insert({
+        Post._get_collection().insert_one({
             "title": "Items eclipse",
             "items": ["more lorem", "even more ipsum"]
         })
@@ -3217,8 +3216,7 @@ class InstanceTest(MongoDBTestCase):
         coll = Person._get_collection()
         for person in Person.objects.as_pymongo():
             if 'height' not in person:
-                person['height'] = 189
-                coll.save(person)
+                coll.update_one({'_id': person['_id']}, {'$set': {'height': 189}})
 
         self.assertEquals(Person.objects(height=189).count(), 1)
 
diff --git a/tests/fields/file_tests.py b/tests/fields/file_tests.py
index 76e20bb9..4ff6865b 100644
--- a/tests/fields/file_tests.py
+++ b/tests/fields/file_tests.py
@@ -24,6 +24,16 @@ 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')
 
 
+def get_file(path):
+    """Use a BytesIO instead of a file to allow
+    to have a one-liner and avoid that the file remains opened"""
+    bytes_io = StringIO()
+    with open(path, 'rb') as f:
+        bytes_io.write(f.read())
+    bytes_io.seek(0)
+    return bytes_io
+
+
 class FileTest(MongoDBTestCase):
 
     def tearDown(self):
@@ -247,8 +257,8 @@ class FileTest(MongoDBTestCase):
         Animal.drop_collection()
         marmot = Animal(genus='Marmota', family='Sciuridae')
 
-        marmot_photo = open(TEST_IMAGE_PATH, 'rb')  # Retrieve a photo from disk
-        marmot.photo.put(marmot_photo, content_type='image/jpeg', foo='bar')
+        marmot_photo_content = get_file(TEST_IMAGE_PATH)  # Retrieve a photo from disk
+        marmot.photo.put(marmot_photo_content, content_type='image/jpeg', foo='bar')
         marmot.photo.close()
         marmot.save()
 
@@ -261,11 +271,11 @@ class FileTest(MongoDBTestCase):
             the_file = FileField()
         TestFile.drop_collection()
 
-        test_file = TestFile(the_file=open(TEST_IMAGE_PATH, 'rb')).save()
+        test_file = TestFile(the_file=get_file(TEST_IMAGE_PATH)).save()
         self.assertEqual(test_file.the_file.get().length, 8313)
 
         test_file = TestFile.objects.first()
-        test_file.the_file = open(TEST_IMAGE2_PATH, 'rb')
+        test_file.the_file = get_file(TEST_IMAGE2_PATH)
         test_file.save()
         self.assertEqual(test_file.the_file.get().length, 4971)
 
@@ -379,7 +389,7 @@ class FileTest(MongoDBTestCase):
                 self.assertEqual("%s" % e, "Invalid image: cannot identify image file %s" % f)
 
         t = TestImage()
-        t.image.put(open(TEST_IMAGE_PATH, 'rb'))
+        t.image.put(get_file(TEST_IMAGE_PATH))
         t.save()
 
         t = TestImage.objects.first()
@@ -400,11 +410,11 @@ class FileTest(MongoDBTestCase):
             the_file = ImageField()
         TestFile.drop_collection()
 
-        test_file = TestFile(the_file=open(TEST_IMAGE_PATH, 'rb')).save()
+        test_file = TestFile(the_file=get_file(TEST_IMAGE_PATH)).save()
         self.assertEqual(test_file.the_file.size, (371, 76))
 
         test_file = TestFile.objects.first()
-        test_file.the_file = open(TEST_IMAGE2_PATH, 'rb')
+        test_file.the_file = get_file(TEST_IMAGE2_PATH)
         test_file.save()
         self.assertEqual(test_file.the_file.size, (45, 101))
 
@@ -418,7 +428,7 @@ class FileTest(MongoDBTestCase):
         TestImage.drop_collection()
 
         t = TestImage()
-        t.image.put(open(TEST_IMAGE_PATH, 'rb'))
+        t.image.put(get_file(TEST_IMAGE_PATH))
         t.save()
 
         t = TestImage.objects.first()
@@ -441,7 +451,7 @@ class FileTest(MongoDBTestCase):
         TestImage.drop_collection()
 
         t = TestImage()
-        t.image.put(open(TEST_IMAGE_PATH, 'rb'))
+        t.image.put(get_file(TEST_IMAGE_PATH))
         t.save()
 
         t = TestImage.objects.first()
@@ -464,7 +474,7 @@ class FileTest(MongoDBTestCase):
         TestImage.drop_collection()
 
         t = TestImage()
-        t.image.put(open(TEST_IMAGE_PATH, 'rb'))
+        t.image.put(get_file(TEST_IMAGE_PATH))
         t.save()
 
         t = TestImage.objects.first()
@@ -542,8 +552,8 @@ class FileTest(MongoDBTestCase):
         TestImage.drop_collection()
 
         t = TestImage()
-        t.image1.put(open(TEST_IMAGE_PATH, 'rb'))
-        t.image2.put(open(TEST_IMAGE2_PATH, 'rb'))
+        t.image1.put(get_file(TEST_IMAGE_PATH))
+        t.image2.put(get_file(TEST_IMAGE2_PATH))
         t.save()
 
         test = TestImage.objects.first()
@@ -563,12 +573,10 @@ class FileTest(MongoDBTestCase):
         Animal.drop_collection()
         marmot = Animal(genus='Marmota', family='Sciuridae')
 
-        marmot_photo = open(TEST_IMAGE_PATH, 'rb')  # Retrieve a photo from disk
-
-        photos_field = marmot._fields['photos'].field
-        new_proxy = photos_field.get_proxy_obj('photos', marmot)
-        new_proxy.put(marmot_photo, content_type='image/jpeg', foo='bar')
-        marmot_photo.close()
+        with open(TEST_IMAGE_PATH, 'rb') as marmot_photo:   # Retrieve a photo from disk
+            photos_field = marmot._fields['photos'].field
+            new_proxy = photos_field.get_proxy_obj('photos', marmot)
+            new_proxy.put(marmot_photo, content_type='image/jpeg', foo='bar')
 
         marmot.photos.append(new_proxy)
         marmot.save()
diff --git a/tests/queryset/queryset.py b/tests/queryset/queryset.py
index 05a7ca75..0d8d6285 100644
--- a/tests/queryset/queryset.py
+++ b/tests/queryset/queryset.py
@@ -19,14 +19,11 @@ from mongoengine.connection import get_connection, get_db
 from mongoengine.context_managers import query_counter, switch_db
 from mongoengine.errors import InvalidQueryError
 from mongoengine.mongodb_support import get_mongodb_version, MONGODB_32
-from mongoengine.python_support import IS_PYMONGO_3
+from mongoengine.pymongo_support import IS_PYMONGO_3
 from mongoengine.queryset import (DoesNotExist, MultipleObjectsReturned,
                                   QuerySet, QuerySetManager, queryset_manager)
-
 from tests.utils import requires_mongodb_gte_26, skip_pymongo3
 
-__all__ = ("QuerySetTest",)
-
 
 class db_ops_tracker(query_counter):
 
@@ -4052,7 +4049,7 @@ class QuerySetTest(unittest.TestCase):
             fielda = IntField()
             fieldb = IntField()
 
-        IntPair.objects._collection.remove()
+        IntPair.drop_collection()
 
         a = IntPair(fielda=1, fieldb=1)
         b = IntPair(fielda=1, fieldb=2)
@@ -5387,7 +5384,7 @@ class QuerySetTest(unittest.TestCase):
 
         Person.drop_collection()
 
-        Person._get_collection().insert({'name': 'a', 'id': ''})
+        Person._get_collection().insert_one({'name': 'a', 'id': ''})
         for p in Person.objects():
             self.assertEqual(p.name, 'a')
 
diff --git a/tests/test_connection.py b/tests/test_connection.py
index 7c4fc4cf..fafef9d4 100644
--- a/tests/test_connection.py
+++ b/tests/test_connection.py
@@ -14,7 +14,7 @@ from mongoengine import (
     connect, register_connection,
     Document, DateTimeField
 )
-from mongoengine.python_support import IS_PYMONGO_3
+from mongoengine.pymongo_support import IS_PYMONGO_3
 import mongoengine.connection
 from mongoengine.connection import (MongoEngineConnectionError, get_db,
                                     get_connection)
@@ -147,12 +147,12 @@ class ConnectionTest(unittest.TestCase):
     def test_connect_uri(self):
         """Ensure that the connect() method works properly with URIs."""
         c = connect(db='mongoenginetest', alias='admin')
-        c.admin.system.users.remove({})
-        c.mongoenginetest.system.users.remove({})
+        c.admin.system.users.delete_many({})
+        c.mongoenginetest.system.users.delete_many({})
 
-        c.admin.add_user("admin", "password")
+        c.admin.command("createUser", "admin", pwd="password", roles=["root"])
         c.admin.authenticate("admin", "password")
-        c.mongoenginetest.add_user("username", "password")
+        c.admin.command("createUser", "username", pwd="password", roles=["dbOwner"])
 
         if not IS_PYMONGO_3:
             self.assertRaises(
@@ -169,8 +169,8 @@ class ConnectionTest(unittest.TestCase):
         self.assertIsInstance(db, pymongo.database.Database)
         self.assertEqual(db.name, 'mongoenginetest')
 
-        c.admin.system.users.remove({})
-        c.mongoenginetest.system.users.remove({})
+        c.admin.system.users.delete_many({})
+        c.mongoenginetest.system.users.delete_many({})
 
     def test_connect_uri_without_db(self):
         """Ensure connect() method works properly if the URI doesn't
@@ -217,8 +217,9 @@ class ConnectionTest(unittest.TestCase):
         """
         # Create users
         c = connect('mongoenginetest')
-        c.admin.system.users.remove({})
-        c.admin.add_user('username2', 'password')
+
+        c.admin.system.users.delete_many({})
+        c.admin.command("createUser", "username2", pwd="password", roles=["dbOwner"])
 
         # Authentication fails without "authSource"
         if IS_PYMONGO_3:
@@ -246,7 +247,7 @@ class ConnectionTest(unittest.TestCase):
         self.assertEqual(db.name, 'mongoenginetest')
 
         # Clear all users
-        authd_conn.admin.system.users.remove({})
+        authd_conn.admin.system.users.delete_many({})
 
     def test_register_connection(self):
         """Ensure that connections with different aliases may be registered.
diff --git a/tests/test_context_managers.py b/tests/test_context_managers.py
index 8207cd89..227031e0 100644
--- a/tests/test_context_managers.py
+++ b/tests/test_context_managers.py
@@ -5,6 +5,7 @@ from mongoengine.connection import get_db
 from mongoengine.context_managers import (switch_db, switch_collection,
                                           no_sub_classes, no_dereference,
                                           query_counter)
+from mongoengine.pymongo_support import count_documents
 
 
 class ContextManagersTest(unittest.TestCase):
@@ -240,7 +241,7 @@ class ContextManagersTest(unittest.TestCase):
         collection.drop()
 
         def issue_1_count_query():
-            collection.find({}).count()
+            count_documents(collection, {})
 
         def issue_1_insert_query():
             collection.insert_one({'test': 'garbage'})
diff --git a/tests/test_replicaset_connection.py b/tests/test_replicaset_connection.py
index 4aa647d6..81fdfb64 100644
--- a/tests/test_replicaset_connection.py
+++ b/tests/test_replicaset_connection.py
@@ -2,7 +2,7 @@ import unittest
 
 from pymongo import ReadPreference
 
-from mongoengine.python_support import IS_PYMONGO_3
+from mongoengine.pymongo_support import IS_PYMONGO_3
 
 if IS_PYMONGO_3:
     from pymongo import MongoClient
diff --git a/tests/utils.py b/tests/utils.py
index e94e4a80..3c41f07d 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -6,7 +6,7 @@ from nose.plugins.skip import SkipTest
 from mongoengine import connect
 from mongoengine.connection import get_db
 from mongoengine.mongodb_support import get_mongodb_version, MONGODB_26, MONGODB_3, MONGODB_32, MONGODB_34
-from mongoengine.python_support import IS_PYMONGO_3
+from mongoengine.pymongo_support import IS_PYMONGO_3
 
 
 MONGO_TEST_DB = 'mongoenginetest'   # standard name for the test database