ocaml-opentelemetry/tests/core/t_histogram.ml
Simon Cruanes 806545f2ba
format
2026-02-21 22:37:10 -05:00

64 lines
2.2 KiB
OCaml

open Opentelemetry
(** A deterministic clock that always returns timestamp 0 *)
let dummy_clock : Clock.t = { Clock.now = (fun () -> 0L) }
let emit h = h.Instrument.emit ~clock:dummy_clock ()
let pp_metrics metrics = List.iter (Format.printf "%a@." Metrics.pp) metrics
(* ------------------------------------------------------------------ *)
(* Test 1: one value per bucket, plus one in the overflow bucket *)
(* bounds [1; 2; 5] → 4 buckets: (≤1) (1,2] (2,5] (5,∞) *)
let () =
let h =
Instrument.Histogram.create ~name:"test.latency"
~description:"test histogram" ~bounds:[ 1.; 2.; 5. ] ()
in
Instrument.Histogram.record h 0.5;
(* bucket 0: ≤1 *)
Instrument.Histogram.record h 1.5;
(* bucket 1: ≤2 *)
Instrument.Histogram.record h 3.0;
(* bucket 2: ≤5 *)
Instrument.Histogram.record h 10.;
(* bucket 3: >5 *)
(* count=4 sum=15.0 bucket_counts=[1;1;1;1] *)
pp_metrics (emit h)
(* ------------------------------------------------------------------ *)
(* Test 2: multiple values pile into the same bucket *)
let () =
let h = Instrument.Histogram.create ~name:"test.size" ~bounds:[ 1.; 5. ] () in
Instrument.Histogram.record h 0.1;
Instrument.Histogram.record h 0.2;
Instrument.Histogram.record h 0.3;
(* 3 values in bucket 0 *)
Instrument.Histogram.record h 2.0;
(* 1 value in bucket 1 *)
(* count=4 sum=2.6 bucket_counts=[3;1;0] *)
pp_metrics (emit h)
(* ------------------------------------------------------------------ *)
(* Test 3: empty histogram *)
let () =
let h =
Instrument.Histogram.create ~name:"test.empty" ~bounds:[ 1.; 2.; 5. ] ()
in
(* count=0 sum=0.0 bucket_counts=[0;0;0;0] *)
pp_metrics (emit h)
(* ------------------------------------------------------------------ *)
(* Test 4: value exactly on a bound goes into that bound's bucket *)
let () =
let h =
Instrument.Histogram.create ~name:"test.boundary" ~bounds:[ 1.; 2.; 5. ] ()
in
Instrument.Histogram.record h 1.0;
(* exactly on bound → bucket 0 *)
Instrument.Histogram.record h 2.0;
(* exactly on bound → bucket 1 *)
Instrument.Histogram.record h 5.0;
(* exactly on bound → bucket 2 *)
(* count=3 sum=8.0 bucket_counts=[1;1;1;0] *)
pp_metrics (emit h)