Allow testing against mongomock

ArchLinux and maybe other Linux distributions have interest in testing
their package of the project, in an environment where MongoDB isn’t
available.

Support for that environment is provided on a best-effort basis. If this
patch ends up being more trouble than it’s worth, please revert it.
Otherwise, let’s be helpful to others. :)

Makefile

@@ -65,6 +65,7 @@ test:
 		-Wdefault:"parameter codeset is deprecated":DeprecationWarning:: \
 		-Wdefault:"'cgi' is deprecated and slated for removal in Python 3.13":DeprecationWarning:: \
 		-Wdefault:"datetime.datetime.utcfromtimestamp() is deprecated and scheduled for removal in a future version.":DeprecationWarning:: \
+		-Wdefault:"pkg_resources is deprecated as an API.":DeprecationWarning:: \
 		-m unittest
 
 # DOC: Test the examples

setup.cfg

@@ -51,6 +51,7 @@ dev =
     SQLAlchemy
     sqlalchemy_utils
     mongoengine
+    mongomock
     wheel>=0.32.0
     tox
     zest.releaser[recommended]

tests/test_mongoengine.py

@@ -6,7 +6,7 @@
 import unittest
 
 try:
-    import mongoengine
+    import mongoengine.connection
 except ImportError:
     raise unittest.SkipTest("mongodb tests disabled.")
 
@@ -38,15 +38,14 @@ class Meta:
     address = factory.SubFactory(AddressFactory)
 
 
-class MongoEngineTestCase(unittest.TestCase):
-
+class BaseMongoEngineTestCase:
     db_name = os.environ.get('MONGO_DATABASE', 'factory_boy_test')
     db_host = os.environ.get('MONGO_HOST', 'localhost')
     db_port = int(os.environ.get('MONGO_PORT', '27017'))
     server_timeout_ms = int(os.environ.get('MONGO_TIMEOUT', '300'))
 
     @classmethod
-    def setUpClass(cls):
+    def setUpClass(cls, **kwargs):
         from pymongo import read_preferences as mongo_rp
         cls.db = mongoengine.connect(
             db=cls.db_name,
@@ -57,11 +56,15 @@ def setUpClass(cls):
             # PyMongo>=2.1 has a 20s timeout, use 100ms instead
             serverselectiontimeoutms=cls.server_timeout_ms,
             uuidRepresentation='standard',
+            **kwargs,
         )
 
     @classmethod
     def tearDownClass(cls):
         cls.db.drop_database(cls.db_name)
+        mongoengine.connection.disconnect()
+        PersonFactory.reset_sequence()
+        AddressFactory.reset_sequence()
 
     def test_build(self):
         std = PersonFactory.build()
@@ -74,3 +77,22 @@ def test_creation(self):
         self.assertEqual('name1', std1.name)
         self.assertEqual('street1', std1.address.street)
         self.assertIsNotNone(std1.id)
+
+
+class MongoEngineTestCase(BaseMongoEngineTestCase, unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        if os.environ.get('MONGO_USE_MOCK', '0') == '1':
+            raise unittest.SkipTest("Using mongomock, do not run the test suite against MongoDB.")
+        super().setUpClass()
+
+
+class MockMongoEngineTestCase(BaseMongoEngineTestCase, unittest.TestCase):
+    """
+    In some environments, MongoDB isn’t available.
+    Run this smoke test instead.
+    """
+    @classmethod
+    def setUpClass(cls):
+        import mongomock
+        super().setUpClass(mongo_client_class=mongomock.MongoClient)

tox.ini

@@ -38,6 +38,9 @@ deps =
     alchemy: SQLAlchemy
     alchemy: sqlalchemy_utils
     mongo: mongoengine
+    mongo: mongomock
+    # mongomock imports pkg_resources, provided by setuptools.
+    mongo: setuptools>=66.1.1
     django{32,42,50,main}: Pillow
     django32: Django>=3.2,<3.3
     django42: Django>=4.2,<5.0