diff --git a/.github/workflows/test-python.yml b/.github/workflows/test-python.yml
index 651f863d89..4b5f762786 100644
--- a/.github/workflows/test-python.yml
+++ b/.github/workflows/test-python.yml
@@ -37,6 +37,7 @@ jobs:
           mongodb-version: 4.4
       - name: Run tests
         run: |
+          pip install mypy
           python setup.py test
 
   mypytest:
@@ -59,4 +60,4 @@ jobs:
       - name: Run mypy
         run: |
           mypy --install-types --non-interactive bson gridfs tools pymongo
-          mypy --install-types --non-interactive --disable-error-code var-annotated --disable-error-code attr-defined --disable-error-code union-attr --disable-error-code assignment --disable-error-code no-redef --disable-error-code index test
+          mypy --install-types --non-interactive --disable-error-code var-annotated --disable-error-code attr-defined --disable-error-code union-attr --disable-error-code assignment --disable-error-code no-redef --disable-error-code index --exclude "test/mypy_fails/*.*" test
diff --git a/test/mypy_fails/insert_many_dict.py b/test/mypy_fails/insert_many_dict.py
new file mode 100644
index 0000000000..6e8acb67b4
--- /dev/null
+++ b/test/mypy_fails/insert_many_dict.py
@@ -0,0 +1,6 @@
+from pymongo import MongoClient
+
+client = MongoClient()
+client.test.test.insert_many(
+    {"a": 1}
+)  # error: Dict entry 0 has incompatible type "str": "int"; expected "Mapping[str, Any]": "int"
diff --git a/test/mypy_fails/insert_one_list.py b/test/mypy_fails/insert_one_list.py
new file mode 100644
index 0000000000..7a26a3ff79
--- /dev/null
+++ b/test/mypy_fails/insert_one_list.py
@@ -0,0 +1,6 @@
+from pymongo import MongoClient
+
+client = MongoClient()
+client.test.test.insert_one(
+    [{}]
+)  # error: Argument 1 to "insert_one" of "Collection" has incompatible type "List[Dict[<nothing>, <nothing>]]"; expected "Mapping[str, Any]"
diff --git a/test/test_bson.py b/test/test_bson.py
index f8f587567d..46aa6e5d9a 100644
--- a/test/test_bson.py
+++ b/test/test_bson.py
@@ -1117,6 +1117,16 @@ def test_int64_pickling(self):
         )
         self.round_trip_pickle(i64, pickled_with_3)
 
+    def test_bson_encode_decode(self) -> None:
+        doc = {"_id": ObjectId()}
+        encoded = bson.encode(doc)
+        decoded = bson.decode(encoded)
+        encoded = bson.encode(decoded)
+        decoded = bson.decode(encoded)
+        # Documents returned from decode are mutable.
+        decoded["new_field"] = 1
+        self.assertTrue(decoded["_id"].generation_time)
+
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/test/test_mypy.py b/test/test_mypy.py
new file mode 100644
index 0000000000..0f1498c64b
--- /dev/null
+++ b/test/test_mypy.py
@@ -0,0 +1,125 @@
+# Copyright 2020-present MongoDB, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Test that each file in mypy_fails/ actually fails mypy, and test some
+sample client code that uses PyMongo typings."""
+
+import os
+import sys
+import unittest
+from typing import Any, Dict, Iterable, List
+
+try:
+    from mypy import api
+except ImportError:
+    api = None
+
+from bson.son import SON
+from pymongo.collection import Collection
+from pymongo.errors import ServerSelectionTimeoutError
+from pymongo.mongo_client import MongoClient
+from pymongo.operations import InsertOne
+
+TEST_PATH = os.path.join(os.path.dirname(os.path.realpath(__file__)), "mypy_fails")
+
+
+def get_tests() -> Iterable[str]:
+    for dirpath, _, filenames in os.walk(TEST_PATH):
+        for filename in filenames:
+            yield os.path.join(dirpath, filename)
+
+
+class TestMypyFails(unittest.TestCase):
+    def ensure_mypy_fails(self, filename: str) -> None:
+        if api is None:
+            raise unittest.SkipTest("Mypy is not installed")
+        stdout, stderr, exit_status = api.run([filename])
+        self.assertTrue(exit_status, msg=stdout)
+
+    def test_mypy_failures(self) -> None:
+        for filename in get_tests():
+            with self.subTest(filename=filename):
+                self.ensure_mypy_fails(filename)
+
+
+class TestPymongo(unittest.TestCase):
+    client: MongoClient
+    coll: Collection
+
+    @classmethod
+    def setUpClass(cls) -> None:
+        cls.client = MongoClient(serverSelectionTimeoutMS=250, directConnection=False)
+        cls.coll = cls.client.test.test
+        try:
+            cls.client.admin.command("ping")
+        except ServerSelectionTimeoutError as exc:
+            raise unittest.SkipTest(f"Could not connect to MongoDB: {exc}")
+
+    @classmethod
+    def tearDownClass(cls) -> None:
+        cls.client.close()
+
+    def test_insert_find(self) -> None:
+        doc = {"my": "doc"}
+        coll2 = self.client.test.test2
+        result = self.coll.insert_one(doc)
+        self.assertEqual(result.inserted_id, doc["_id"])
+        retreived = self.coll.find_one({"_id": doc["_id"]})
+        if retreived:
+            # Documents returned from find are mutable.
+            retreived["new_field"] = 1
+            result2 = coll2.insert_one(retreived)
+            self.assertEqual(result2.inserted_id, result.inserted_id)
+
+    def test_cursor_iterable(self) -> None:
+        def to_list(iterable: Iterable[Dict[str, Any]]) -> List[Dict[str, Any]]:
+            return list(iterable)
+
+        self.coll.insert_one({})
+        cursor = self.coll.find()
+        docs = to_list(cursor)
+        self.assertTrue(docs)
+
+    def test_bulk_write(self) -> None:
+        self.coll.insert_one({})
+        requests = [InsertOne({})]
+        result = self.coll.bulk_write(requests)
+        self.assertTrue(result.acknowledged)
+
+    def test_aggregate_pipeline(self) -> None:
+        coll3 = self.client.test.test3
+        coll3.insert_many(
+            [
+                {"x": 1, "tags": ["dog", "cat"]},
+                {"x": 2, "tags": ["cat"]},
+                {"x": 2, "tags": ["mouse", "cat", "dog"]},
+                {"x": 3, "tags": []},
+            ]
+        )
+
+        class mydict(Dict[str, Any]):
+            pass
+
+        result = coll3.aggregate(
+            [
+                mydict({"$unwind": "$tags"}),
+                {"$group": {"_id": "$tags", "count": {"$sum": 1}}},
+                {"$sort": SON([("count", -1), ("_id", -1)])},
+            ]
+        )
+        self.assertTrue(len(list(result)))
+
+
+if __name__ == "__main__":
+    unittest.main()