diff --git a/gridfs/asynchronous/grid_file.py b/gridfs/asynchronous/grid_file.py
index d15713c51b..baa88d4808 100644
--- a/gridfs/asynchronous/grid_file.py
+++ b/gridfs/asynchronous/grid_file.py
@@ -231,7 +231,7 @@ async def get_version(
         try:
             doc = await anext(cursor)
             return AsyncGridOut(self._collection, file_document=doc, session=session)
-        except StopIteration:
+        except StopAsyncIteration:
             raise NoFile("no version %d for filename %r" % (version, filename)) from None
 
     async def get_last_version(
diff --git a/test/asynchronous/test_gridfs.py b/test/asynchronous/test_gridfs.py
new file mode 100644
index 0000000000..b1c1e754ff
--- /dev/null
+++ b/test/asynchronous/test_gridfs.py
@@ -0,0 +1,602 @@
+#
+# Copyright 2009-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.
+
+"""Tests for the gridfs package."""
+from __future__ import annotations
+
+import asyncio
+import datetime
+import sys
+import threading
+import time
+from io import BytesIO
+from test.asynchronous.helpers import ConcurrentRunner
+from unittest.mock import patch
+
+sys.path[0:0] = [""]
+
+from test.asynchronous import AsyncIntegrationTest, async_client_context, unittest
+from test.utils import async_joinall, one
+
+import gridfs
+from bson.binary import Binary
+from gridfs.asynchronous.grid_file import DEFAULT_CHUNK_SIZE, AsyncGridOutCursor
+from gridfs.errors import CorruptGridFile, FileExists, NoFile
+from pymongo.asynchronous.database import AsyncDatabase
+from pymongo.asynchronous.mongo_client import AsyncMongoClient
+from pymongo.errors import (
+    ConfigurationError,
+    NotPrimaryError,
+    ServerSelectionTimeoutError,
+)
+from pymongo.read_preferences import ReadPreference
+
+_IS_SYNC = False
+
+
+class JustWrite(ConcurrentRunner):
+    def __init__(self, fs, n):
+        super().__init__()
+        self.fs = fs
+        self.n = n
+        self.daemon = True
+
+    async def run(self):
+        for _ in range(self.n):
+            file = self.fs.new_file(filename="test")
+            await file.write(b"hello")
+            await file.close()
+
+
+class JustRead(ConcurrentRunner):
+    def __init__(self, fs, n, results):
+        super().__init__()
+        self.fs = fs
+        self.n = n
+        self.results = results
+        self.daemon = True
+
+    async def run(self):
+        for _ in range(self.n):
+            file = await self.fs.get("test")
+            data = await file.read()
+            self.results.append(data)
+            assert data == b"hello"
+
+
+class TestGridfsNoConnect(unittest.IsolatedAsyncioTestCase):
+    db: AsyncDatabase
+
+    async def asyncSetUp(self):
+        await super().asyncSetUp()
+        self.db = AsyncMongoClient(connect=False).pymongo_test
+
+    async def test_gridfs(self):
+        self.assertRaises(TypeError, gridfs.AsyncGridFS, "foo")
+        self.assertRaises(TypeError, gridfs.AsyncGridFS, self.db, 5)
+
+
+class TestGridfs(AsyncIntegrationTest):
+    fs: gridfs.AsyncGridFS
+    alt: gridfs.AsyncGridFS
+
+    async def asyncSetUp(self):
+        await super().asyncSetUp()
+        self.fs = gridfs.AsyncGridFS(self.db)
+        self.alt = gridfs.AsyncGridFS(self.db, "alt")
+        await self.cleanup_colls(
+            self.db.fs.files, self.db.fs.chunks, self.db.alt.files, self.db.alt.chunks
+        )
+
+    async def test_basic(self):
+        oid = await self.fs.put(b"hello world")
+        self.assertEqual(b"hello world", await (await self.fs.get(oid)).read())
+        self.assertEqual(1, await self.db.fs.files.count_documents({}))
+        self.assertEqual(1, await self.db.fs.chunks.count_documents({}))
+
+        await self.fs.delete(oid)
+        with self.assertRaises(NoFile):
+            await self.fs.get(oid)
+        self.assertEqual(0, await self.db.fs.files.count_documents({}))
+        self.assertEqual(0, await self.db.fs.chunks.count_documents({}))
+
+        with self.assertRaises(NoFile):
+            await self.fs.get("foo")
+        oid = await self.fs.put(b"hello world", _id="foo")
+        self.assertEqual("foo", oid)
+        self.assertEqual(b"hello world", await (await self.fs.get("foo")).read())
+
+    async def test_multi_chunk_delete(self):
+        await self.db.fs.drop()
+        self.assertEqual(0, await self.db.fs.files.count_documents({}))
+        self.assertEqual(0, await self.db.fs.chunks.count_documents({}))
+        gfs = gridfs.AsyncGridFS(self.db)
+        oid = await gfs.put(b"hello", chunkSize=1)
+        self.assertEqual(1, await self.db.fs.files.count_documents({}))
+        self.assertEqual(5, await self.db.fs.chunks.count_documents({}))
+        await gfs.delete(oid)
+        self.assertEqual(0, await self.db.fs.files.count_documents({}))
+        self.assertEqual(0, await self.db.fs.chunks.count_documents({}))
+
+    async def test_list(self):
+        self.assertEqual([], await self.fs.list())
+        await self.fs.put(b"hello world")
+        self.assertEqual([], await self.fs.list())
+
+        # PYTHON-598: in server versions before 2.5.x, creating an index on
+        # filename, uploadDate causes list() to include None.
+        await self.fs.get_last_version()
+        self.assertEqual([], await self.fs.list())
+
+        await self.fs.put(b"", filename="mike")
+        await self.fs.put(b"foo", filename="test")
+        await self.fs.put(b"", filename="hello world")
+
+        self.assertEqual({"mike", "test", "hello world"}, set(await self.fs.list()))
+
+    async def test_empty_file(self):
+        oid = await self.fs.put(b"")
+        self.assertEqual(b"", await (await self.fs.get(oid)).read())
+        self.assertEqual(1, await self.db.fs.files.count_documents({}))
+        self.assertEqual(0, await self.db.fs.chunks.count_documents({}))
+
+        raw = await self.db.fs.files.find_one()
+        assert raw is not None
+        self.assertEqual(0, raw["length"])
+        self.assertEqual(oid, raw["_id"])
+        self.assertTrue(isinstance(raw["uploadDate"], datetime.datetime))
+        self.assertEqual(255 * 1024, raw["chunkSize"])
+        self.assertNotIn("md5", raw)
+
+    async def test_corrupt_chunk(self):
+        files_id = await self.fs.put(b"foobar")
+        await self.db.fs.chunks.update_one(
+            {"files_id": files_id}, {"$set": {"data": Binary(b"foo", 0)}}
+        )
+        try:
+            out = await self.fs.get(files_id)
+            with self.assertRaises(CorruptGridFile):
+                await out.read()
+
+            out = await self.fs.get(files_id)
+            with self.assertRaises(CorruptGridFile):
+                await out.readline()
+        finally:
+            await self.fs.delete(files_id)
+
+    async def test_put_ensures_index(self):
+        chunks = self.db.fs.chunks
+        files = self.db.fs.files
+        # Ensure the collections are removed.
+        await chunks.drop()
+        await files.drop()
+        await self.fs.put(b"junk")
+
+        self.assertTrue(
+            any(
+                info.get("key") == [("files_id", 1), ("n", 1)]
+                for info in (await chunks.index_information()).values()
+            )
+        )
+        self.assertTrue(
+            any(
+                info.get("key") == [("filename", 1), ("uploadDate", 1)]
+                for info in (await files.index_information()).values()
+            )
+        )
+
+    async def test_alt_collection(self):
+        oid = await self.alt.put(b"hello world")
+        self.assertEqual(b"hello world", await (await self.alt.get(oid)).read())
+        self.assertEqual(1, await self.db.alt.files.count_documents({}))
+        self.assertEqual(1, await self.db.alt.chunks.count_documents({}))
+
+        await self.alt.delete(oid)
+        with self.assertRaises(NoFile):
+            await self.alt.get(oid)
+        self.assertEqual(0, await self.db.alt.files.count_documents({}))
+        self.assertEqual(0, await self.db.alt.chunks.count_documents({}))
+
+        with self.assertRaises(NoFile):
+            await self.alt.get("foo")
+        oid = await self.alt.put(b"hello world", _id="foo")
+        self.assertEqual("foo", oid)
+        self.assertEqual(b"hello world", await (await self.alt.get("foo")).read())
+
+        await self.alt.put(b"", filename="mike")
+        await self.alt.put(b"foo", filename="test")
+        await self.alt.put(b"", filename="hello world")
+
+        self.assertEqual({"mike", "test", "hello world"}, set(await self.alt.list()))
+
+    async def test_threaded_reads(self):
+        await self.fs.put(b"hello", _id="test")
+
+        tasks = []
+        results: list = []
+        for i in range(10):
+            tasks.append(JustRead(self.fs, 10, results))
+            await tasks[i].start()
+
+        await async_joinall(tasks)
+
+        self.assertEqual(100 * [b"hello"], results)
+
+    async def test_threaded_writes(self):
+        tasks = []
+        for i in range(10):
+            tasks.append(JustWrite(self.fs, 10))
+            await tasks[i].start()
+
+        await async_joinall(tasks)
+
+        f = await self.fs.get_last_version("test")
+        self.assertEqual(await f.read(), b"hello")
+
+        # Should have created 100 versions of 'test' file
+        self.assertEqual(100, await self.db.fs.files.count_documents({"filename": "test"}))
+
+    async def test_get_last_version(self):
+        one = await self.fs.put(b"foo", filename="test")
+        await asyncio.sleep(0.01)
+        two = self.fs.new_file(filename="test")
+        await two.write(b"bar")
+        await two.close()
+        await asyncio.sleep(0.01)
+        two = two._id
+        three = await self.fs.put(b"baz", filename="test")
+
+        self.assertEqual(b"baz", await (await self.fs.get_last_version("test")).read())
+        await self.fs.delete(three)
+        self.assertEqual(b"bar", await (await self.fs.get_last_version("test")).read())
+        await self.fs.delete(two)
+        self.assertEqual(b"foo", await (await self.fs.get_last_version("test")).read())
+        await self.fs.delete(one)
+        with self.assertRaises(NoFile):
+            await self.fs.get_last_version("test")
+
+    async def test_get_last_version_with_metadata(self):
+        one = await self.fs.put(b"foo", filename="test", author="author")
+        await asyncio.sleep(0.01)
+        two = await self.fs.put(b"bar", filename="test", author="author")
+
+        self.assertEqual(b"bar", await (await self.fs.get_last_version(author="author")).read())
+        await self.fs.delete(two)
+        self.assertEqual(b"foo", await (await self.fs.get_last_version(author="author")).read())
+        await self.fs.delete(one)
+
+        one = await self.fs.put(b"foo", filename="test", author="author1")
+        await asyncio.sleep(0.01)
+        two = await self.fs.put(b"bar", filename="test", author="author2")
+
+        self.assertEqual(b"foo", await (await self.fs.get_last_version(author="author1")).read())
+        self.assertEqual(b"bar", await (await self.fs.get_last_version(author="author2")).read())
+        self.assertEqual(b"bar", await (await self.fs.get_last_version(filename="test")).read())
+
+        with self.assertRaises(NoFile):
+            await self.fs.get_last_version(author="author3")
+        with self.assertRaises(NoFile):
+            await self.fs.get_last_version(filename="nottest", author="author1")
+
+        await self.fs.delete(one)
+        await self.fs.delete(two)
+
+    async def test_get_version(self):
+        await self.fs.put(b"foo", filename="test")
+        await asyncio.sleep(0.01)
+        await self.fs.put(b"bar", filename="test")
+        await asyncio.sleep(0.01)
+        await self.fs.put(b"baz", filename="test")
+        await asyncio.sleep(0.01)
+
+        self.assertEqual(b"foo", await (await self.fs.get_version("test", 0)).read())
+        self.assertEqual(b"bar", await (await self.fs.get_version("test", 1)).read())
+        self.assertEqual(b"baz", await (await self.fs.get_version("test", 2)).read())
+
+        self.assertEqual(b"baz", await (await self.fs.get_version("test", -1)).read())
+        self.assertEqual(b"bar", await (await self.fs.get_version("test", -2)).read())
+        self.assertEqual(b"foo", await (await self.fs.get_version("test", -3)).read())
+
+        with self.assertRaises(NoFile):
+            await self.fs.get_version("test", 3)
+        with self.assertRaises(NoFile):
+            await self.fs.get_version("test", -4)
+
+    async def test_get_version_with_metadata(self):
+        one = await self.fs.put(b"foo", filename="test", author="author1")
+        await asyncio.sleep(0.01)
+        two = await self.fs.put(b"bar", filename="test", author="author1")
+        await asyncio.sleep(0.01)
+        three = await self.fs.put(b"baz", filename="test", author="author2")
+
+        self.assertEqual(
+            b"foo",
+            await (await self.fs.get_version(filename="test", author="author1", version=-2)).read(),
+        )
+        self.assertEqual(
+            b"bar",
+            await (await self.fs.get_version(filename="test", author="author1", version=-1)).read(),
+        )
+        self.assertEqual(
+            b"foo",
+            await (await self.fs.get_version(filename="test", author="author1", version=0)).read(),
+        )
+        self.assertEqual(
+            b"bar",
+            await (await self.fs.get_version(filename="test", author="author1", version=1)).read(),
+        )
+        self.assertEqual(
+            b"baz",
+            await (await self.fs.get_version(filename="test", author="author2", version=0)).read(),
+        )
+        self.assertEqual(
+            b"baz", await (await self.fs.get_version(filename="test", version=-1)).read()
+        )
+        self.assertEqual(
+            b"baz", await (await self.fs.get_version(filename="test", version=2)).read()
+        )
+
+        with self.assertRaises(NoFile):
+            await self.fs.get_version(filename="test", author="author3")
+        with self.assertRaises(NoFile):
+            await self.fs.get_version(filename="test", author="author1", version=2)
+
+        await self.fs.delete(one)
+        await self.fs.delete(two)
+        await self.fs.delete(three)
+
+    async def test_put_filelike(self):
+        oid = await self.fs.put(BytesIO(b"hello world"), chunk_size=1)
+        self.assertEqual(11, await self.db.fs.chunks.count_documents({}))
+        self.assertEqual(b"hello world", await (await self.fs.get(oid)).read())
+
+    async def test_file_exists(self):
+        oid = await self.fs.put(b"hello")
+        with self.assertRaises(FileExists):
+            await self.fs.put(b"world", _id=oid)
+
+        one = self.fs.new_file(_id=123)
+        await one.write(b"some content")
+        await one.close()
+
+        # Attempt to upload a file with more chunks to the same _id.
+        with patch("gridfs.asynchronous.grid_file._UPLOAD_BUFFER_SIZE", DEFAULT_CHUNK_SIZE):
+            two = self.fs.new_file(_id=123)
+            with self.assertRaises(FileExists):
+                await two.write(b"x" * DEFAULT_CHUNK_SIZE * 3)
+        # Original file is still readable (no extra chunks were uploaded).
+        self.assertEqual(await (await self.fs.get(123)).read(), b"some content")
+
+        two = self.fs.new_file(_id=123)
+        await two.write(b"some content")
+        with self.assertRaises(FileExists):
+            await two.close()
+        # Original file is still readable.
+        self.assertEqual(await (await self.fs.get(123)).read(), b"some content")
+
+    async def test_exists(self):
+        oid = await self.fs.put(b"hello")
+        self.assertTrue(await self.fs.exists(oid))
+        self.assertTrue(await self.fs.exists({"_id": oid}))
+        self.assertTrue(await self.fs.exists(_id=oid))
+
+        self.assertFalse(await self.fs.exists(filename="mike"))
+        self.assertFalse(await self.fs.exists("mike"))
+
+        oid = await self.fs.put(b"hello", filename="mike", foo=12)
+        self.assertTrue(await self.fs.exists(oid))
+        self.assertTrue(await self.fs.exists({"_id": oid}))
+        self.assertTrue(await self.fs.exists(_id=oid))
+        self.assertTrue(await self.fs.exists(filename="mike"))
+        self.assertTrue(await self.fs.exists({"filename": "mike"}))
+        self.assertTrue(await self.fs.exists(foo=12))
+        self.assertTrue(await self.fs.exists({"foo": 12}))
+        self.assertTrue(await self.fs.exists(foo={"$gt": 11}))
+        self.assertTrue(await self.fs.exists({"foo": {"$gt": 11}}))
+
+        self.assertFalse(await self.fs.exists(foo=13))
+        self.assertFalse(await self.fs.exists({"foo": 13}))
+        self.assertFalse(await self.fs.exists(foo={"$gt": 12}))
+        self.assertFalse(await self.fs.exists({"foo": {"$gt": 12}}))
+
+    async def test_put_unicode(self):
+        with self.assertRaises(TypeError):
+            await self.fs.put("hello")
+
+        oid = await self.fs.put("hello", encoding="utf-8")
+        self.assertEqual(b"hello", await (await self.fs.get(oid)).read())
+        self.assertEqual("utf-8", (await self.fs.get(oid)).encoding)
+
+        oid = await self.fs.put("aé", encoding="iso-8859-1")
+        self.assertEqual("aé".encode("iso-8859-1"), await (await self.fs.get(oid)).read())
+        self.assertEqual("iso-8859-1", (await self.fs.get(oid)).encoding)
+
+    async def test_missing_length_iter(self):
+        # Test fix that guards against PHP-237
+        await self.fs.put(b"", filename="empty")
+        doc = await self.db.fs.files.find_one({"filename": "empty"})
+        assert doc is not None
+        doc.pop("length")
+        await self.db.fs.files.replace_one({"_id": doc["_id"]}, doc)
+        f = await self.fs.get_last_version(filename="empty")
+
+        async def iterate_file(grid_file):
+            async for _chunk in grid_file:
+                pass
+            return True
+
+        self.assertTrue(await iterate_file(f))
+
+    async def test_gridfs_lazy_connect(self):
+        client = await self.async_single_client(
+            "badhost", connect=False, serverSelectionTimeoutMS=10
+        )
+        db = client.db
+        gfs = gridfs.AsyncGridFS(db)
+        with self.assertRaises(ServerSelectionTimeoutError):
+            await gfs.list()
+
+        fs = gridfs.AsyncGridFS(db)
+        f = fs.new_file()
+        with self.assertRaises(ServerSelectionTimeoutError):
+            await f.close()
+
+    async def test_gridfs_find(self):
+        await self.fs.put(b"test2", filename="two")
+        await asyncio.sleep(0.01)
+        await self.fs.put(b"test2+", filename="two")
+        await asyncio.sleep(0.01)
+        await self.fs.put(b"test1", filename="one")
+        await asyncio.sleep(0.01)
+        await self.fs.put(b"test2++", filename="two")
+        files = self.db.fs.files
+        self.assertEqual(3, await files.count_documents({"filename": "two"}))
+        self.assertEqual(4, await files.count_documents({}))
+        cursor = self.fs.find(no_cursor_timeout=False).sort("uploadDate", -1).skip(1).limit(2)
+        gout = await cursor.next()
+        self.assertEqual(b"test1", await gout.read())
+        await cursor.rewind()
+        gout = await cursor.next()
+        self.assertEqual(b"test1", await gout.read())
+        gout = await cursor.next()
+        self.assertEqual(b"test2+", await gout.read())
+        with self.assertRaises(StopAsyncIteration):
+            await cursor.__anext__()
+        await cursor.rewind()
+        items = await cursor.to_list()
+        self.assertEqual(len(items), 2)
+        await cursor.rewind()
+        items = await cursor.to_list(1)
+        self.assertEqual(len(items), 1)
+        await cursor.close()
+        self.assertRaises(TypeError, self.fs.find, {}, {"_id": True})
+
+    async def test_delete_not_initialized(self):
+        # Creating a cursor with invalid arguments will not run __init__
+        # but will still call __del__.
+        cursor = AsyncGridOutCursor.__new__(AsyncGridOutCursor)  # Skip calling __init__
+        with self.assertRaises(TypeError):
+            cursor.__init__(self.db.fs.files, {}, {"_id": True})  # type: ignore
+        cursor.__del__()  # no error
+
+    async def test_gridfs_find_one(self):
+        self.assertEqual(None, await self.fs.find_one())
+
+        id1 = await self.fs.put(b"test1", filename="file1")
+        res = await self.fs.find_one()
+        assert res is not None
+        self.assertEqual(b"test1", await res.read())
+
+        id2 = await self.fs.put(b"test2", filename="file2", meta="data")
+        res1 = await self.fs.find_one(id1)
+        assert res1 is not None
+        self.assertEqual(b"test1", await res1.read())
+        res2 = await self.fs.find_one(id2)
+        assert res2 is not None
+        self.assertEqual(b"test2", await res2.read())
+
+        res3 = await self.fs.find_one({"filename": "file1"})
+        assert res3 is not None
+        self.assertEqual(b"test1", await res3.read())
+
+        res4 = await self.fs.find_one(id2)
+        assert res4 is not None
+        self.assertEqual("data", res4.meta)
+
+    async def test_grid_in_non_int_chunksize(self):
+        # Lua, and perhaps other buggy AsyncGridFS clients, store size as a float.
+        data = b"data"
+        await self.fs.put(data, filename="f")
+        await self.db.fs.files.update_one({"filename": "f"}, {"$set": {"chunkSize": 100.0}})
+
+        self.assertEqual(data, await (await self.fs.get_version("f")).read())
+
+    async def test_unacknowledged(self):
+        # w=0 is prohibited.
+        with self.assertRaises(ConfigurationError):
+            gridfs.AsyncGridFS((await self.async_rs_or_single_client(w=0)).pymongo_test)
+
+    async def test_md5(self):
+        gin = self.fs.new_file()
+        await gin.write(b"no md5 sum")
+        await gin.close()
+        self.assertIsNone(gin.md5)
+
+        gout = await self.fs.get(gin._id)
+        self.assertIsNone(gout.md5)
+
+        _id = await self.fs.put(b"still no md5 sum")
+        gout = await self.fs.get(_id)
+        self.assertIsNone(gout.md5)
+
+
+class TestGridfsReplicaSet(AsyncIntegrationTest):
+    @async_client_context.require_secondaries_count(1)
+    async def asyncSetUp(self):
+        await super().asyncSetUp()
+
+    @classmethod
+    @async_client_context.require_connection
+    async def asyncTearDownClass(cls):
+        await async_client_context.client.drop_database("gfsreplica")
+
+    async def test_gridfs_replica_set(self):
+        rsc = await self.async_rs_client(
+            w=async_client_context.w, read_preference=ReadPreference.SECONDARY
+        )
+
+        fs = gridfs.AsyncGridFS(rsc.gfsreplica, "gfsreplicatest")
+
+        gin = fs.new_file()
+        self.assertEqual(gin._coll.read_preference, ReadPreference.PRIMARY)
+
+        oid = await fs.put(b"foo")
+        content = await (await fs.get(oid)).read()
+        self.assertEqual(b"foo", content)
+
+    async def test_gridfs_secondary(self):
+        secondary_host, secondary_port = one(await self.client.secondaries)
+        secondary_connection = await self.async_single_client(
+            secondary_host, secondary_port, read_preference=ReadPreference.SECONDARY
+        )
+
+        # Should detect it's connected to secondary and not attempt to
+        # create index
+        fs = gridfs.AsyncGridFS(secondary_connection.gfsreplica, "gfssecondarytest")
+
+        # This won't detect secondary, raises error
+        with self.assertRaises(NotPrimaryError):
+            await fs.put(b"foo")
+
+    async def test_gridfs_secondary_lazy(self):
+        # Should detect it's connected to secondary and not attempt to
+        # create index.
+        secondary_host, secondary_port = one(await self.client.secondaries)
+        client = await self.async_single_client(
+            secondary_host, secondary_port, read_preference=ReadPreference.SECONDARY, connect=False
+        )
+
+        # Still no connection.
+        fs = gridfs.AsyncGridFS(client.gfsreplica, "gfssecondarylazytest")
+
+        # Connects, doesn't create index.
+        with self.assertRaises(NoFile):
+            await fs.get_last_version()
+        with self.assertRaises(NotPrimaryError):
+            await fs.put("data", encoding="utf-8")
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/test/test_gridfs.py b/test/test_gridfs.py
index ab8950250b..47e38141b2 100644
--- a/test/test_gridfs.py
+++ b/test/test_gridfs.py
@@ -16,11 +16,13 @@
 """Tests for the gridfs package."""
 from __future__ import annotations
 
+import asyncio
 import datetime
 import sys
 import threading
 import time
 from io import BytesIO
+from test.helpers import ConcurrentRunner
 from unittest.mock import patch
 
 sys.path[0:0] = [""]
@@ -41,10 +43,12 @@
 from pymongo.synchronous.database import Database
 from pymongo.synchronous.mongo_client import MongoClient
 
+_IS_SYNC = True
 
-class JustWrite(threading.Thread):
+
+class JustWrite(ConcurrentRunner):
     def __init__(self, fs, n):
-        threading.Thread.__init__(self)
+        super().__init__()
         self.fs = fs
         self.n = n
         self.daemon = True
@@ -56,9 +60,9 @@ def run(self):
             file.close()
 
 
-class JustRead(threading.Thread):
+class JustRead(ConcurrentRunner):
     def __init__(self, fs, n, results):
-        threading.Thread.__init__(self)
+        super().__init__()
         self.fs = fs
         self.n = n
         self.results = results
@@ -98,19 +102,21 @@ def setUp(self):
 
     def test_basic(self):
         oid = self.fs.put(b"hello world")
-        self.assertEqual(b"hello world", self.fs.get(oid).read())
+        self.assertEqual(b"hello world", (self.fs.get(oid)).read())
         self.assertEqual(1, self.db.fs.files.count_documents({}))
         self.assertEqual(1, self.db.fs.chunks.count_documents({}))
 
         self.fs.delete(oid)
-        self.assertRaises(NoFile, self.fs.get, oid)
+        with self.assertRaises(NoFile):
+            self.fs.get(oid)
         self.assertEqual(0, self.db.fs.files.count_documents({}))
         self.assertEqual(0, self.db.fs.chunks.count_documents({}))
 
-        self.assertRaises(NoFile, self.fs.get, "foo")
+        with self.assertRaises(NoFile):
+            self.fs.get("foo")
         oid = self.fs.put(b"hello world", _id="foo")
         self.assertEqual("foo", oid)
-        self.assertEqual(b"hello world", self.fs.get("foo").read())
+        self.assertEqual(b"hello world", (self.fs.get("foo")).read())
 
     def test_multi_chunk_delete(self):
         self.db.fs.drop()
@@ -142,7 +148,7 @@ def test_list(self):
 
     def test_empty_file(self):
         oid = self.fs.put(b"")
-        self.assertEqual(b"", self.fs.get(oid).read())
+        self.assertEqual(b"", (self.fs.get(oid)).read())
         self.assertEqual(1, self.db.fs.files.count_documents({}))
         self.assertEqual(0, self.db.fs.chunks.count_documents({}))
 
@@ -159,10 +165,12 @@ def test_corrupt_chunk(self):
         self.db.fs.chunks.update_one({"files_id": files_id}, {"$set": {"data": Binary(b"foo", 0)}})
         try:
             out = self.fs.get(files_id)
-            self.assertRaises(CorruptGridFile, out.read)
+            with self.assertRaises(CorruptGridFile):
+                out.read()
 
             out = self.fs.get(files_id)
-            self.assertRaises(CorruptGridFile, out.readline)
+            with self.assertRaises(CorruptGridFile):
+                out.readline()
         finally:
             self.fs.delete(files_id)
 
@@ -177,31 +185,33 @@ def test_put_ensures_index(self):
         self.assertTrue(
             any(
                 info.get("key") == [("files_id", 1), ("n", 1)]
-                for info in chunks.index_information().values()
+                for info in (chunks.index_information()).values()
             )
         )
         self.assertTrue(
             any(
                 info.get("key") == [("filename", 1), ("uploadDate", 1)]
-                for info in files.index_information().values()
+                for info in (files.index_information()).values()
             )
         )
 
     def test_alt_collection(self):
         oid = self.alt.put(b"hello world")
-        self.assertEqual(b"hello world", self.alt.get(oid).read())
+        self.assertEqual(b"hello world", (self.alt.get(oid)).read())
         self.assertEqual(1, self.db.alt.files.count_documents({}))
         self.assertEqual(1, self.db.alt.chunks.count_documents({}))
 
         self.alt.delete(oid)
-        self.assertRaises(NoFile, self.alt.get, oid)
+        with self.assertRaises(NoFile):
+            self.alt.get(oid)
         self.assertEqual(0, self.db.alt.files.count_documents({}))
         self.assertEqual(0, self.db.alt.chunks.count_documents({}))
 
-        self.assertRaises(NoFile, self.alt.get, "foo")
+        with self.assertRaises(NoFile):
+            self.alt.get("foo")
         oid = self.alt.put(b"hello world", _id="foo")
         self.assertEqual("foo", oid)
-        self.assertEqual(b"hello world", self.alt.get("foo").read())
+        self.assertEqual(b"hello world", (self.alt.get("foo")).read())
 
         self.alt.put(b"", filename="mike")
         self.alt.put(b"foo", filename="test")
@@ -212,23 +222,23 @@ def test_alt_collection(self):
     def test_threaded_reads(self):
         self.fs.put(b"hello", _id="test")
 
-        threads = []
+        tasks = []
         results: list = []
         for i in range(10):
-            threads.append(JustRead(self.fs, 10, results))
-            threads[i].start()
+            tasks.append(JustRead(self.fs, 10, results))
+            tasks[i].start()
 
-        joinall(threads)
+        joinall(tasks)
 
         self.assertEqual(100 * [b"hello"], results)
 
     def test_threaded_writes(self):
-        threads = []
+        tasks = []
         for i in range(10):
-            threads.append(JustWrite(self.fs, 10))
-            threads[i].start()
+            tasks.append(JustWrite(self.fs, 10))
+            tasks[i].start()
 
-        joinall(threads)
+        joinall(tasks)
 
         f = self.fs.get_last_version("test")
         self.assertEqual(f.read(), b"hello")
@@ -246,34 +256,37 @@ def test_get_last_version(self):
         two = two._id
         three = self.fs.put(b"baz", filename="test")
 
-        self.assertEqual(b"baz", self.fs.get_last_version("test").read())
+        self.assertEqual(b"baz", (self.fs.get_last_version("test")).read())
         self.fs.delete(three)
-        self.assertEqual(b"bar", self.fs.get_last_version("test").read())
+        self.assertEqual(b"bar", (self.fs.get_last_version("test")).read())
         self.fs.delete(two)
-        self.assertEqual(b"foo", self.fs.get_last_version("test").read())
+        self.assertEqual(b"foo", (self.fs.get_last_version("test")).read())
         self.fs.delete(one)
-        self.assertRaises(NoFile, self.fs.get_last_version, "test")
+        with self.assertRaises(NoFile):
+            self.fs.get_last_version("test")
 
     def test_get_last_version_with_metadata(self):
         one = self.fs.put(b"foo", filename="test", author="author")
         time.sleep(0.01)
         two = self.fs.put(b"bar", filename="test", author="author")
 
-        self.assertEqual(b"bar", self.fs.get_last_version(author="author").read())
+        self.assertEqual(b"bar", (self.fs.get_last_version(author="author")).read())
         self.fs.delete(two)
-        self.assertEqual(b"foo", self.fs.get_last_version(author="author").read())
+        self.assertEqual(b"foo", (self.fs.get_last_version(author="author")).read())
         self.fs.delete(one)
 
         one = self.fs.put(b"foo", filename="test", author="author1")
         time.sleep(0.01)
         two = self.fs.put(b"bar", filename="test", author="author2")
 
-        self.assertEqual(b"foo", self.fs.get_last_version(author="author1").read())
-        self.assertEqual(b"bar", self.fs.get_last_version(author="author2").read())
-        self.assertEqual(b"bar", self.fs.get_last_version(filename="test").read())
+        self.assertEqual(b"foo", (self.fs.get_last_version(author="author1")).read())
+        self.assertEqual(b"bar", (self.fs.get_last_version(author="author2")).read())
+        self.assertEqual(b"bar", (self.fs.get_last_version(filename="test")).read())
 
-        self.assertRaises(NoFile, self.fs.get_last_version, author="author3")
-        self.assertRaises(NoFile, self.fs.get_last_version, filename="nottest", author="author1")
+        with self.assertRaises(NoFile):
+            self.fs.get_last_version(author="author3")
+        with self.assertRaises(NoFile):
+            self.fs.get_last_version(filename="nottest", author="author1")
 
         self.fs.delete(one)
         self.fs.delete(two)
@@ -286,16 +299,18 @@ def test_get_version(self):
         self.fs.put(b"baz", filename="test")
         time.sleep(0.01)
 
-        self.assertEqual(b"foo", self.fs.get_version("test", 0).read())
-        self.assertEqual(b"bar", self.fs.get_version("test", 1).read())
-        self.assertEqual(b"baz", self.fs.get_version("test", 2).read())
+        self.assertEqual(b"foo", (self.fs.get_version("test", 0)).read())
+        self.assertEqual(b"bar", (self.fs.get_version("test", 1)).read())
+        self.assertEqual(b"baz", (self.fs.get_version("test", 2)).read())
 
-        self.assertEqual(b"baz", self.fs.get_version("test", -1).read())
-        self.assertEqual(b"bar", self.fs.get_version("test", -2).read())
-        self.assertEqual(b"foo", self.fs.get_version("test", -3).read())
+        self.assertEqual(b"baz", (self.fs.get_version("test", -1)).read())
+        self.assertEqual(b"bar", (self.fs.get_version("test", -2)).read())
+        self.assertEqual(b"foo", (self.fs.get_version("test", -3)).read())
 
-        self.assertRaises(NoFile, self.fs.get_version, "test", 3)
-        self.assertRaises(NoFile, self.fs.get_version, "test", -4)
+        with self.assertRaises(NoFile):
+            self.fs.get_version("test", 3)
+        with self.assertRaises(NoFile):
+            self.fs.get_version("test", -4)
 
     def test_get_version_with_metadata(self):
         one = self.fs.put(b"foo", filename="test", author="author1")
@@ -305,25 +320,32 @@ def test_get_version_with_metadata(self):
         three = self.fs.put(b"baz", filename="test", author="author2")
 
         self.assertEqual(
-            b"foo", self.fs.get_version(filename="test", author="author1", version=-2).read()
+            b"foo",
+            (self.fs.get_version(filename="test", author="author1", version=-2)).read(),
         )
         self.assertEqual(
-            b"bar", self.fs.get_version(filename="test", author="author1", version=-1).read()
+            b"bar",
+            (self.fs.get_version(filename="test", author="author1", version=-1)).read(),
         )
         self.assertEqual(
-            b"foo", self.fs.get_version(filename="test", author="author1", version=0).read()
+            b"foo",
+            (self.fs.get_version(filename="test", author="author1", version=0)).read(),
         )
         self.assertEqual(
-            b"bar", self.fs.get_version(filename="test", author="author1", version=1).read()
+            b"bar",
+            (self.fs.get_version(filename="test", author="author1", version=1)).read(),
         )
         self.assertEqual(
-            b"baz", self.fs.get_version(filename="test", author="author2", version=0).read()
+            b"baz",
+            (self.fs.get_version(filename="test", author="author2", version=0)).read(),
         )
-        self.assertEqual(b"baz", self.fs.get_version(filename="test", version=-1).read())
-        self.assertEqual(b"baz", self.fs.get_version(filename="test", version=2).read())
+        self.assertEqual(b"baz", (self.fs.get_version(filename="test", version=-1)).read())
+        self.assertEqual(b"baz", (self.fs.get_version(filename="test", version=2)).read())
 
-        self.assertRaises(NoFile, self.fs.get_version, filename="test", author="author3")
-        self.assertRaises(NoFile, self.fs.get_version, filename="test", author="author1", version=2)
+        with self.assertRaises(NoFile):
+            self.fs.get_version(filename="test", author="author3")
+        with self.assertRaises(NoFile):
+            self.fs.get_version(filename="test", author="author1", version=2)
 
         self.fs.delete(one)
         self.fs.delete(two)
@@ -332,11 +354,12 @@ def test_get_version_with_metadata(self):
     def test_put_filelike(self):
         oid = self.fs.put(BytesIO(b"hello world"), chunk_size=1)
         self.assertEqual(11, self.db.fs.chunks.count_documents({}))
-        self.assertEqual(b"hello world", self.fs.get(oid).read())
+        self.assertEqual(b"hello world", (self.fs.get(oid)).read())
 
     def test_file_exists(self):
         oid = self.fs.put(b"hello")
-        self.assertRaises(FileExists, self.fs.put, b"world", _id=oid)
+        with self.assertRaises(FileExists):
+            self.fs.put(b"world", _id=oid)
 
         one = self.fs.new_file(_id=123)
         one.write(b"some content")
@@ -345,15 +368,17 @@ def test_file_exists(self):
         # Attempt to upload a file with more chunks to the same _id.
         with patch("gridfs.synchronous.grid_file._UPLOAD_BUFFER_SIZE", DEFAULT_CHUNK_SIZE):
             two = self.fs.new_file(_id=123)
-            self.assertRaises(FileExists, two.write, b"x" * DEFAULT_CHUNK_SIZE * 3)
+            with self.assertRaises(FileExists):
+                two.write(b"x" * DEFAULT_CHUNK_SIZE * 3)
         # Original file is still readable (no extra chunks were uploaded).
-        self.assertEqual(self.fs.get(123).read(), b"some content")
+        self.assertEqual((self.fs.get(123)).read(), b"some content")
 
         two = self.fs.new_file(_id=123)
         two.write(b"some content")
-        self.assertRaises(FileExists, two.close)
+        with self.assertRaises(FileExists):
+            two.close()
         # Original file is still readable.
-        self.assertEqual(self.fs.get(123).read(), b"some content")
+        self.assertEqual((self.fs.get(123)).read(), b"some content")
 
     def test_exists(self):
         oid = self.fs.put(b"hello")
@@ -381,15 +406,16 @@ def test_exists(self):
         self.assertFalse(self.fs.exists({"foo": {"$gt": 12}}))
 
     def test_put_unicode(self):
-        self.assertRaises(TypeError, self.fs.put, "hello")
+        with self.assertRaises(TypeError):
+            self.fs.put("hello")
 
         oid = self.fs.put("hello", encoding="utf-8")
-        self.assertEqual(b"hello", self.fs.get(oid).read())
-        self.assertEqual("utf-8", self.fs.get(oid).encoding)
+        self.assertEqual(b"hello", (self.fs.get(oid)).read())
+        self.assertEqual("utf-8", (self.fs.get(oid)).encoding)
 
         oid = self.fs.put("aé", encoding="iso-8859-1")
-        self.assertEqual("aé".encode("iso-8859-1"), self.fs.get(oid).read())
-        self.assertEqual("iso-8859-1", self.fs.get(oid).encoding)
+        self.assertEqual("aé".encode("iso-8859-1"), (self.fs.get(oid)).read())
+        self.assertEqual("iso-8859-1", (self.fs.get(oid)).encoding)
 
     def test_missing_length_iter(self):
         # Test fix that guards against PHP-237
@@ -411,11 +437,13 @@ def test_gridfs_lazy_connect(self):
         client = self.single_client("badhost", connect=False, serverSelectionTimeoutMS=10)
         db = client.db
         gfs = gridfs.GridFS(db)
-        self.assertRaises(ServerSelectionTimeoutError, gfs.list)
+        with self.assertRaises(ServerSelectionTimeoutError):
+            gfs.list()
 
         fs = gridfs.GridFS(db)
         f = fs.new_file()
-        self.assertRaises(ServerSelectionTimeoutError, f.close)
+        with self.assertRaises(ServerSelectionTimeoutError):
+            f.close()
 
     def test_gridfs_find(self):
         self.fs.put(b"test2", filename="two")
@@ -429,14 +457,15 @@ def test_gridfs_find(self):
         self.assertEqual(3, files.count_documents({"filename": "two"}))
         self.assertEqual(4, files.count_documents({}))
         cursor = self.fs.find(no_cursor_timeout=False).sort("uploadDate", -1).skip(1).limit(2)
-        gout = next(cursor)
+        gout = cursor.next()
         self.assertEqual(b"test1", gout.read())
         cursor.rewind()
-        gout = next(cursor)
+        gout = cursor.next()
         self.assertEqual(b"test1", gout.read())
-        gout = next(cursor)
+        gout = cursor.next()
         self.assertEqual(b"test2+", gout.read())
-        self.assertRaises(StopIteration, cursor.__next__)
+        with self.assertRaises(StopIteration):
+            cursor.__next__()
         cursor.rewind()
         items = cursor.to_list()
         self.assertEqual(len(items), 2)
@@ -484,12 +513,12 @@ def test_grid_in_non_int_chunksize(self):
         self.fs.put(data, filename="f")
         self.db.fs.files.update_one({"filename": "f"}, {"$set": {"chunkSize": 100.0}})
 
-        self.assertEqual(data, self.fs.get_version("f").read())
+        self.assertEqual(data, (self.fs.get_version("f")).read())
 
     def test_unacknowledged(self):
         # w=0 is prohibited.
         with self.assertRaises(ConfigurationError):
-            gridfs.GridFS(self.rs_or_single_client(w=0).pymongo_test)
+            gridfs.GridFS((self.rs_or_single_client(w=0)).pymongo_test)
 
     def test_md5(self):
         gin = self.fs.new_file()
@@ -524,7 +553,7 @@ def test_gridfs_replica_set(self):
         self.assertEqual(gin._coll.read_preference, ReadPreference.PRIMARY)
 
         oid = fs.put(b"foo")
-        content = fs.get(oid).read()
+        content = (fs.get(oid)).read()
         self.assertEqual(b"foo", content)
 
     def test_gridfs_secondary(self):
@@ -538,7 +567,8 @@ def test_gridfs_secondary(self):
         fs = gridfs.GridFS(secondary_connection.gfsreplica, "gfssecondarytest")
 
         # This won't detect secondary, raises error
-        self.assertRaises(NotPrimaryError, fs.put, b"foo")
+        with self.assertRaises(NotPrimaryError):
+            fs.put(b"foo")
 
     def test_gridfs_secondary_lazy(self):
         # Should detect it's connected to secondary and not attempt to
@@ -552,8 +582,10 @@ def test_gridfs_secondary_lazy(self):
         fs = gridfs.GridFS(client.gfsreplica, "gfssecondarylazytest")
 
         # Connects, doesn't create index.
-        self.assertRaises(NoFile, fs.get_last_version)
-        self.assertRaises(NotPrimaryError, fs.put, "data", encoding="utf-8")
+        with self.assertRaises(NoFile):
+            fs.get_last_version()
+        with self.assertRaises(NotPrimaryError):
+            fs.put("data", encoding="utf-8")
 
 
 if __name__ == "__main__":
diff --git a/test/utils.py b/test/utils.py
index 5c1e0bfb7c..40eec01cb4 100644
--- a/test/utils.py
+++ b/test/utils.py
@@ -666,6 +666,11 @@ def joinall(threads):
         assert not t.is_alive(), "Thread %s hung" % t
 
 
+async def async_joinall(tasks):
+    """Join threads with a 5-minute timeout, assert joins succeeded"""
+    await asyncio.wait([t.task for t in tasks if t is not None], timeout=300)
+
+
 def wait_until(predicate, success_description, timeout=10):
     """Wait up to 10 seconds (by default) for predicate to be true.
 
diff --git a/tools/synchro.py b/tools/synchro.py
index 7e7aeec3a4..8fec7627ea 100644
--- a/tools/synchro.py
+++ b/tools/synchro.py
@@ -122,7 +122,9 @@
     "SpecRunnerTask": "SpecRunnerThread",
     "AsyncMockConnection": "MockConnection",
     "AsyncMockPool": "MockPool",
+    "StopAsyncIteration": "StopIteration",
     "create_async_event": "create_event",
+    "async_joinall": "joinall",
 }
 
 docstring_replacements: dict[tuple[str, str], str] = {
@@ -212,12 +214,13 @@ def async_only_test(f: str) -> bool:
     "test_dns.py",
     "test_encryption.py",
     "test_examples.py",
+    "test_grid_file.py",
+    "test_gridfs.py",
+    "test_gridfs_spec.py",
     "test_heartbeat_monitoring.py",
     "test_index_management.py",
-    "test_grid_file.py",
-    "test_load_balancer.py",
     "test_json_util_integration.py",
-    "test_gridfs_spec.py",
+    "test_load_balancer.py",
     "test_logger.py",
     "test_max_staleness.py",
     "test_monitoring.py",