Add tests for consul service discovery (#2490)
Add tests for consul service discovery (#2490)

* Add tests for consul service discovery

* Add license header

* Address comments

* inline variables
* check for extra error

* Fix error formatting

kangwoo/prometheus,GoogleCloudPlatform/prometheus,amorken/prometheus,brancz/prometheus,kangwoo/prometheus,Conorbro/prometheus,brancz/prometheus,yanghongkjxy/prometheus,GoogleCloudPlatform/prometheus,prometheus/prometheus,dsymonds/prometheus,AlekSi/prometheus,agaoglu/prometheus,Stackdriver/stackdriver-prometheus,kzittritsch/prometheus,agaoglu/prometheus,kangwoo/prometheus,JavierZunzunegui/prometheus,agaoglu/prometheus,brancz/prometheus,alileza/prometheus,yanghongkjxy/prometheus,tomwilkie/prometheus,GoogleCloudPlatform/prometheus,kangwoo/prometheus,SaltedMan/prometheus-annotated,prometheus/prometheus,dsymonds/prometheus,JavierZunzunegui/prometheus,alileza/prometheus,alileza/prometheus,keegancsmith/prometheus,Colstuwjx/prometheus,amorken/prometheus,Colstuwjx/prometheus,Conorbro/prometheus,keegancsmith/prometheus,Conorbro/prometheus,JavierZunzunegui/prometheus,tomwilkie/prometheus,Stackdriver/stackdriver-prometheus,JavierZunzunegui/prometheus,GoogleCloudPlatform/prometheus,Colstuwjx/prometheus,prometheus/prometheus,brancz/prometheus,SaltedMan/prometheus-annotated,prometheus/prometheus,yanghongkjxy/prometheus,Colstuwjx/prometheus,GoogleCloudPlatform/prometheus,Gouthamve/prometheus,keegancsmith/prometheus,Stackdriver/stackdriver-prometheus,yanghongkjxy/prometheus,Conorbro/prometheus,Gouthamve/prometheus,tomwilkie/prometheus,alileza/prometheus,AlekSi/prometheus,Stackdriver/stackdriver-prometheus,amorken/prometheus,keegancsmith/prometheus,dsymonds/prometheus,alileza/prometheus,keegancsmith/prometheus,kzittritsch/prometheus,SaltedMan/prometheus-annotated,kzittritsch/prometheus,tomwilkie/prometheus,Gouthamve/prometheus,AlekSi/prometheus,AlekSi/prometheus,Gouthamve/prometheus,amorken/prometheus,prometheus/prometheus,dsymonds/prometheus,kzittritsch/prometheus,SaltedMan/prometheus-annotated,agaoglu/prometheus