trace-tef: additional argument to with_setup; env for "stdout"/"stderr"

src/tef/trace_tef.ml

@@ -316,12 +316,14 @@ let setup ?(out = `Env) () =
       let path = "trace.json" in
       let c = collector ~out:(`File path) () in
       Trace.setup_collector c
+    | Some "stdout" -> Trace.setup_collector @@ collector ~out:`Stdout ()
+    | Some "stderr" -> Trace.setup_collector @@ collector ~out:`Stderr ()
     | Some path ->
       let c = collector ~out:(`File path) () in
       Trace.setup_collector c
     | None -> ())
 
-let with_setup ?out f =
+let with_setup ?out () f =
   setup ?out ();
   protect ~finally:Trace.shutdown f
 

src/tef/trace_tef.mli

@@ -24,13 +24,18 @@ val setup : ?out:[ output | `Env ] -> unit -> unit
     - [`Env] will enable tracing if the environment
       variable "TRACE" is set.
 
-      If it's set to anything but "1", the value is taken
+      - If it's set to "1", then the file is "trace.json".
+      - If it's set to "stdout", then logging happens on stdout (since 0.2)
+      - If it's set to "stderr", then logging happens on stdout (since 0.2)
+      - Otherwise, if it's set to a non empty string, the value is taken
         to be the file path into which to write.
-      If it's set to "1", then the file is "trace.json".
 *)
 
-val with_setup : ?out:[ output | `Env ] -> (unit -> 'a) -> 'a
-(** Setup, and make sure to shutdown before exiting *)
+val with_setup : ?out:[ output | `Env ] -> unit -> (unit -> 'a) -> 'a
+(** [with_setup () f] (optionally) sets a collector up, calls [f()],
+    and makes sure to shutdown before exiting.
+    since 0.2 a () argument was added.
+*)
 
 (**/**)
 

test/t1.ml

@@ -17,4 +17,4 @@ let run () =
 
 let () =
   Trace_tef.Internal_.mock_all_ ();
-  Trace_tef.with_setup ~out:`Stdout @@ fun () -> run ()
+  Trace_tef.with_setup ~out:`Stdout () @@ fun () -> run ()