diff --git a/test_s3.py b/test_s3.py
new file mode 100644
index 0000000..379d381
--- /dev/null
+++ b/test_s3.py
@@ -0,0 +1,181 @@
+# -*- coding: utf-8 -*-
+# Copyright 2018 New Vector Ltd
+#
+# 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.
+
+from twisted.internet import defer
+from twisted.python.failure import Failure
+from twisted.test.proto_helpers import MemoryReactorClock
+from twisted.trial import unittest
+
+from queue import Queue
+from threading import Event, Thread
+
+from mock import Mock
+
+from s3_storage_provider import (
+    _stream_to_producer, _S3Responder, _ProducerStatus,
+)
+
+
+class StreamingProducerTestCase(unittest.TestCase):
+    def setUp(self):
+        self.reactor = ThreadedMemoryReactorClock()
+
+        self.body = Channel()
+        self.consumer = Mock()
+        self.written = ""
+
+        def write(data):
+            self.written += data
+
+        self.consumer.write.side_effect = write
+
+        self.producer_status = _ProducerStatus()
+        self.producer = _S3Responder()
+        self.thread = Thread(
+            target=_stream_to_producer,
+            args=(self.reactor, self.producer, self.body),
+            kwargs={
+                "status": self.producer_status,
+                "timeout": 1.0,
+            },
+        )
+        self.thread.daemon = True
+        self.thread.start()
+
+    def tearDown(self):
+        # Really ensure that we've stopped the thread
+        self.producer.stopProducing()
+
+    def test_simple_produce(self):
+        deferred = self.producer.write_to_consumer(self.consumer)
+
+        self.body.write("test")
+        self.wait_for_thread()
+        self.assertEqual("test", self.written)
+
+        self.body.write(" string")
+        self.wait_for_thread()
+        self.assertEqual("test string", self.written)
+
+        self.body.finish()
+        self.wait_for_thread()
+
+        self.assertTrue(deferred.called)
+        self.assertEqual(deferred.result, None)
+
+    def test_pause_produce(self):
+        deferred = self.producer.write_to_consumer(self.consumer)
+
+        self.body.write("test")
+        self.wait_for_thread()
+        self.assertEqual("test", self.written)
+
+        # We pause producing, but the thread will currently be blocked waiting
+        # to read data, so we wake it up by writing before asserting that
+        # it actually pauses.
+        self.producer.pauseProducing()
+        self.body.write(" string")
+        self.wait_for_thread()
+        self.producer_status.wait_until_paused(10.)
+        self.assertEqual("test string", self.written)
+
+        # If we write again we remain paused and nothing gets written
+        self.body.write(" second")
+        self.producer_status.wait_until_paused(10.)
+        self.assertEqual("test string", self.written)
+
+        # If we call resumeProducing the buffered data gets read and written.
+        self.producer.resumeProducing()
+        self.wait_for_thread()
+        self.assertEqual("test string second", self.written)
+
+        # We can continue writing as normal now
+        self.body.write(" third")
+        self.wait_for_thread()
+        self.assertEqual("test string second third", self.written)
+
+        self.body.finish()
+        self.wait_for_thread()
+
+        self.assertTrue(deferred.called)
+        self.assertEqual(deferred.result, None)
+
+    def test_error(self):
+        deferred = self.producer.write_to_consumer(self.consumer)
+
+        self.body.write("test")
+        self.wait_for_thread()
+        self.assertEqual("test", self.written)
+
+        excp = Exception("Test Exception")
+        self.body.error(excp)
+        self.wait_for_thread()
+
+        self.assertTrue(deferred.called)
+        self.assertIsInstance(deferred.result, Failure)
+
+    def wait_for_thread(self):
+        """Wait for something to call `callFromThread` and advance reactor
+        """
+        self.reactor.thread_event.wait(1)
+        self.reactor.thread_event.clear()
+        self.reactor.advance(0)
+
+
+class ThreadedMemoryReactorClock(MemoryReactorClock):
+    """
+    A MemoryReactorClock that supports callFromThread.
+    """
+
+    def __init__(self):
+        super(ThreadedMemoryReactorClock, self).__init__()
+        self.thread_event = Event()
+
+    def callFromThread(self, callback, *args, **kwargs):
+        """
+        Make the callback fire in the next reactor iteration.
+        """
+        d = defer.Deferred()
+        d.addCallback(lambda x: callback(*args, **kwargs))
+        self.callLater(0, d.callback, True)
+
+        self.thread_event.set()
+
+        return d
+
+
+class Channel(object):
+    """Simple channel to mimic a thread safe file like object
+    """
+    def __init__(self):
+        self._queue = Queue()
+
+    def read(self, _):
+        val = self._queue.get()
+        if isinstance(val, Exception):
+            raise val
+        return val
+
+    def write(self, val):
+        self._queue.put(val)
+
+    def error(self, err):
+        self._queue.put(err)
+
+    def finish(self):
+        self._queue.put(None)
+
+    def close(self):
+        pass