prometheus: adapt unit tests
prometheus: adapt unit tests

jescarri/prometheus-operator,brancz/prometheus-operator,mmerrill3/prometheus-operator,brancz/prometheus-operator,gianrubio/prometheus-operator,mmerrill3/prometheus-operator,brancz/prometheus-operator,gianrubio/prometheus-operator,coreos/prometheus-operator,coreos/prometheus-operator,eedugon/prometheus-operator,jescarri/prometheus-operator,gianrubio/prometheus-operator,mmerrill3/prometheus-operator,eedugon/prometheus-operator