From 6e8877f17711675cbbedaa8cae35ff8e73b72f2b Mon Sep 17 00:00:00 2001
From: Simon Cruanes <simon.cruanes.2007@m4x.org>
Date: Thu, 30 Oct 2025 22:05:08 -0400
Subject: [PATCH] test: reference test for encoding size

---
 tests/core/dune            |  4 ++--
 tests/core/t_size.expected |  1 +
 tests/core/t_size.ml       | 22 ++++++++++++++++++++++
 3 files changed, 25 insertions(+), 2 deletions(-)
 create mode 100644 tests/core/t_size.expected
 create mode 100644 tests/core/t_size.ml

diff --git a/tests/core/dune b/tests/core/dune
index 8a702b10..77d2b02f 100644
--- a/tests/core/dune
+++ b/tests/core/dune
@@ -1,4 +1,4 @@
 (tests
- (names test_trace_context)
+ (names test_trace_context t_size)
  (package opentelemetry)
- (libraries opentelemetry))
+ (libraries opentelemetry opentelemetry.client))
diff --git a/tests/core/t_size.expected b/tests/core/t_size.expected
new file mode 100644
index 00000000..391ca120
--- /dev/null
+++ b/tests/core/t_size.expected
@@ -0,0 +1 @@
+metrics size: 492B
diff --git a/tests/core/t_size.ml b/tests/core/t_size.ml
new file mode 100644
index 00000000..97e989df
--- /dev/null
+++ b/tests/core/t_size.ml
@@ -0,0 +1,22 @@
+(* test the size of serialized data *)
+
+open Opentelemetry
+
+let m =
+  Metrics.make_resource_metrics
+    [
+      Metrics.sum ~name:"sum.foo"
+        [
+          Metrics.int ~start_time_unix_nano:42L ~now:45L 10;
+          Metrics.int ~start_time_unix_nano:52L ~now:55L 20;
+        ];
+      Metrics.gauge ~name:"gauge.bar"
+        [
+          Metrics.float ~start_time_unix_nano:42L ~now:45L 10.;
+          Metrics.float ~start_time_unix_nano:52L ~now:55L 20.;
+        ];
+    ]
+
+let () =
+  let str = Opentelemetry_client.Signal.Encode.metrics [ m; m ] in
+  Printf.printf "metrics size: %dB\n" (String.length str)