Can BDD work for Big Data ETL testing?

I was wandering if anyone uses BDD for testing a Big Data ETL application? I can see how BDD can be used for testing applications having a client interact with them, but in case of Big Data ETL application there is no client interaction so its hard to see what 'When' I might use. For example: Give 100 event of type A occur And 50 event of type B occur after 5 minute Then database rows should be: |Type|Count|Bucket| |A|100|1| |B|50|2|

But that seems wrong. Any one with an insight?