spall test

test/dune

@@ -12,6 +12,12 @@
   (pps ppx_trace))
  (libraries trace-tef))
 
+(test
+ (name t_spall)
+ (package trace-spall)
+ (modules t_spall)
+ (libraries trace trace-spall))
+
 (test
  (name t_runtime_events)
  (package trace-runtime-events)

test/t_spall.ml

@@ -0,0 +1,36 @@
+module Trace = Trace_core
+
+let () =
+  Trace_spall.Private_.mock_all_ ();
+  let path = Filename.temp_file "test_spall" ".spall" in
+  Fun.protect
+    ~finally:(fun () -> try Sys.remove path with _ -> ())
+    (fun () ->
+      Trace_spall.with_setup ~out:(`File path) () (fun () ->
+          Trace.set_process_name "test";
+          Trace.set_thread_name "main";
+          Trace.with_span ~__FILE__ ~__LINE__ "outer" (fun _sp ->
+              Trace.with_span ~__FILE__ ~__LINE__ "inner" (fun _sp -> ())));
+
+      (* verify the binary header *)
+      let ic = open_in_bin path in
+      Fun.protect
+        ~finally:(fun () -> close_in ic)
+        (fun () ->
+          let read_u64 () =
+            let b = Bytes.create 8 in
+            really_input ic b 0 8;
+            (* little-endian u64 *)
+            let r = ref Int64.zero in
+            for i = 7 downto 0 do
+              r :=
+                Int64.add (Int64.shift_left !r 8)
+                  (Int64.of_int (Char.code (Bytes.get b i)))
+            done;
+            !r
+          in
+          let magic = read_u64 () in
+          assert (magic = 0x0BADF00DL);
+          let version = read_u64 () in
+          assert (version = 3L);
+          Printf.printf "magic=0x%LX version=%Ld OK\n" magic version))