test: extract recorder used for ambient tests

test/common/dune

@@ -0,0 +1,3 @@
+(library
+ (name test_trace_common)
+ (libraries trace.core))

test/common/test_trace_common.ml

@@ -0,0 +1,32 @@
+(** Shared test utilities for ambient span tests. *)
+
+type Trace_core.span += Named of string
+
+let make_recorder () =
+  let open Trace_core.Collector in
+  let cbs =
+    Callbacks.make
+      ~enter_span:(fun
+          ()
+          ~__FUNCTION__:_
+          ~__FILE__:_
+          ~__LINE__:_
+          ~level:_
+          ~params:_
+          ~data:_
+          ~parent:_
+          name
+        -> Named name)
+      ~exit_span:(fun () _sp -> ())
+      ~add_data_to_span:(fun () _sp _data -> ())
+      ~message:(fun () ~level:_ ~params:_ ~data:_ ~span:_ _msg -> ())
+      ~metric:(fun () ~level:_ ~params:_ ~data:_ _name _m -> ())
+      ()
+  in
+  C_some ((), cbs)
+
+let current_name () =
+  match Trace_core.current_span () with
+  | None -> "none"
+  | Some (Named s) -> s
+  | Some _ -> "<other>"

test/tls/dune

@@ -3,8 +3,7 @@
  (modules t_tls)
  (libraries
   trace
-  ; avoid using a recent dune with `enabled-if`, by just using `select` instead.
-  ; the dummy case just echoes back the expected file.
+  test_trace_common
   (select
    t_tls.ml
    from

test/tls/t_tls.real.ml

@@ -1,39 +1,9 @@
 (* Test ambient span tracking via thread-local-storage provider *)
 
+open Test_trace_common
+
 let ( let@ ) = ( @@ )
 
-(* Unique span type so we can identify spans by name *)
-type Trace_core.span += Named of string
-
-let make_recorder () =
-  let open Trace_core.Collector in
-  let cbs =
-    Callbacks.make
-      ~enter_span:(fun
-          ()
-          ~__FUNCTION__:_
-          ~__FILE__:_
-          ~__LINE__:_
-          ~level:_
-          ~params:_
-          ~data:_
-          ~parent:_
-          name
-        -> Named name)
-      ~exit_span:(fun () _sp -> ())
-      ~add_data_to_span:(fun () _sp _data -> ())
-      ~message:(fun () ~level:_ ~params:_ ~data:_ ~span:_ _msg -> ())
-      ~metric:(fun () ~level:_ ~params:_ ~data:_ _name _m -> ())
-      ()
-  in
-  C_some ((), cbs)
-
-let current_name () =
-  match Trace_core.current_span () with
-  | None -> "none"
-  | Some (Named s) -> s
-  | Some _ -> "<other>"
-
 let () =
   print_endline "=== ambient span (TLS) ===";
   Trace_thread_local_storage.setup ();