Show the unexpected error on our fuzzer

Author: dinosaure

miou/tests/dune

@@ -8,6 +8,8 @@
    ptime
    ptime.clock.os
    crowbar
+   hxd.core
+   hxd.string
    tls-miou-unix)
  (instrumentation
   (backend bisect_ppx)))

miou/tests/fuzz.ml

@@ -248,6 +248,9 @@ let compile to_client to_server =
   go 0x0 to_client to_server;
   (Buffer.contents client, Buffer.contents server)
 
+let pp_exn ppf exn = Fmt.string ppf (Printexc.to_string exn)
+let pp_str ppf str = Hxd_string.pp Hxd.default ppf str
+
 let run seed operations =
   Miou_unix.run ~domains:1 @@ fun () ->
   let rng = Mirage_crypto_rng_miou_unix.(initialize (module Pfortuna)) in
@@ -278,9 +281,12 @@ let run seed operations =
       let m = String.length send_to_server in
       Mirage_crypto_rng_miou_unix.kill rng;
       epr "[%a] %db %db transmitted\n%!" Fmt.(styled `Green string) "OK" n m
-  | _ ->
+  | a, b ->
       Mirage_crypto_rng_miou_unix.kill rng;
-      Crowbar.failf "[%a] Unexpected result\n%!" Fmt.(styled `Red string) "ERROR"
+      Crowbar.failf "[%a] Unexpected result: %a & %a\n%!"
+        Fmt.(styled `Red string) "ERROR"
+        Fmt.(Dump.result ~error:pp_exn ~ok:Fmt.(Dump.list (Dump.result ~error:pp_exn ~ok:pp_str))) a
+        Fmt.(Dump.result ~error:pp_exn ~ok:pp_str) b
 
 let label name gen = Crowbar.with_printer Fmt.(const string name) gen
 

tls-miou-unix.opam

@@ -17,13 +17,14 @@ depends: [
   "ocaml" {>= "5.0.0"}
   "dune" {>= "3.0"}
   "tls" {= version}
-  "mirage-crypto-rng-miou-unix" {>= "1.0.0"}
+  "mirage-crypto-rng-miou-unix" {>= "1.0.0" & with-test}
   "x509" {>= "1.0.0"}
   "miou" {>= "0.2.0"}
   "crowbar" {with-test}
   "rresult" {with-test}
   "ohex" {with-test}
   "ptime" {with-test}
+  "hxd" {with-test}
 ]
 tags: [ "org:mirage"]
 synopsis: "Transport Layer Security purely in OCaml, Miou+Unix layer"