Add ability to insert custom sources and sinks

Closes-bug: PROD-35310
Change-Id: I3e9877f4aa48cee23c6839e5ab33f01a02e4bcd4
diff --git a/tests/pip_requirements.txt b/tests/pip_requirements.txt
index 940ecbb..4d8fa16 100644
--- a/tests/pip_requirements.txt
+++ b/tests/pip_requirements.txt
@@ -1,2 +1,3 @@
 jsonschema
 setuptools<45.0.0
+msgpack<1