anchor.diff:    ?_assertEqual("# TYPE pool_size gauge
   # HELP pool_size MongoDB Connections pool size
   pool_size 365
  +# TYPE dtest counter
  +# HELP dtest qwe
  +dtest 6.5
   # TYPE http_requests_total counter
   # HELP http_requests_total Http request count
   http_requests_total 1
  -# TYPE dtest counter
  -# HELP dtest qwe
  -dtest 6.5
   # TYPE orders_summary summary
   # HELP orders_summary Track orders count/total sum
   orders_summary_count 2
   orders_summary_sum 25
  +# TYPE dsummary summary
  +# HELP dsummary qwe
  +dsummary_count 2
  +dsummary_sum 4.2
   # TYPE http_request_duration_milliseconds histogram
   # HELP http_request_duration_milliseconds Http Request execution time
  +http_request_duration_milliseconds_bucket{method=\"post\",le=\"100\"} 0
  +http_request_duration_milliseconds_bucket{method=\"post\",le=\"300\"} 1
  +http_request_duration_milliseconds_bucket{method=\"post\",le=\"500\"} 3
  +http_request_duration_milliseconds_bucket{method=\"post\",le=\"750\"} 4
  +http_request_duration_milliseconds_bucket{method=\"post\",le=\"1000\"} 5
  +http_request_duration_milliseconds_bucket{method=\"post\",le=\"+Inf\"} 6
  +http_request_duration_milliseconds_count{method=\"post\"} 6
  +http_request_duration_milliseconds_sum{method=\"post\"} 4350
   http_request_duration_milliseconds_bucket{method=\"get\",le=\"100\"} 3
   http_request_duration_milliseconds_bucket{method=\"get\",le=\"300\"} 6
   http_request_duration_milliseconds_bucket{method=\"get\",le=\"500\"} 7
  
positive.code: 
  test_format() ->
    prometheus_gauge:new([{name, pool_size}, {help, "MongoDB Connections pool size"}]),
    prometheus_counter:new([{name, http_requests_total}, {help, "Http request count"}]),  
    prometheus_counter:new([{name, dtest}, {help, "qwe"}]),
    prometheus_summary:new([{name, orders_summary}, {help, "Track orders count/total sum"}]),
    prometheus_histogram:new([{name, http_request_duration_milliseconds},
                              {labels, [method]},
                              {bounds, [100, 300, 500, 750, 1000]},
  
negative.code: http_request_duration_milliseconds_bucket{method=\"get\",le=\"+Inf\"} 9
  http_request_duration_milliseconds_count{method=\"get\"} 9
  http_request_duration_milliseconds_sum{method=\"get\"} 2622
  
  ",
                  binary_to_list(prometheus_text_format:format())).
  