CBQE-1904: tuq: added tests for nest expression

Change-Id: I4066d34d9d0be54f784170ac305f80765bc2141c
Reviewed-on: http://review.couchbase.org/32907
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Ketaki Gangal <ketakigangal@gmail.com>