datastore: adds tests for anonymous struct fields
datastore: adds tests for anonymous struct fields

Change-Id: I12af350708af8895602d7685077f153b4a947aef
Reviewed-on: https://code-review.googlesource.com/6930
Reviewed-by: Jaana Burcu Dogan <347c19a639ce752a783b4ea325d6539ab4b4a262@google.com>
Reviewed-by: Tuo Shan <e38988508c7dd9b59ee1f5735040284711960df8@google.com>
Reviewed-by: Ross Light <dfccc06f14414bff5a59be7fc90abf4404b47fc8@google.com>

michael-grosshans/google-cloud-go,googleapis/google-cloud-go,googleapis/google-cloud-go,googleapis/google-cloud-go,michael-grosshans/google-cloud-go,googleapis/google-cloud-go