Add a test for storing an event without an associated batch.
Add a test for storing an event without an associated batch.

TouK/vumi,vishwaprakashmishra/xmatrix,harrissoerja/vumi,TouK/vumi,harrissoerja/vumi,harrissoerja/vumi,vishwaprakashmishra/xmatrix,vishwaprakashmishra/xmatrix,TouK/vumi