added match_raises a generalized version of check_raises

CHANGES.md

@@ -1,5 +1,8 @@
 ### unreleased
 
+- Add `match_raises`, a generalized version of `check_raises`
+  (#88, #386, @JoanThibault)
+
 ### 1.7.0 (2023-02-24)
 
 - Allow skipping a test case from inside the test case (#368, @apeschar)

src/alcotest-engine/test.ml

@@ -239,5 +239,18 @@ let check_raises ?here ?pos msg exn f =
             Fmt.pf ppf "%t%a %s: expecting %s, got %s." (pp_location ?here ?pos)
               Pp.tag `Fail msg (Printexc.to_string exn) (Printexc.to_string e))
 
+let match_raises ?here ?pos msg exnp f =
+  show_assert msg;
+  match collect_exception f with
+  | None ->
+      check_err (fun ppf () ->
+          Fmt.pf ppf "%t%a %s: got nothing." (pp_location ?here ?pos) Pp.tag
+            `Fail msg)
+  | Some e ->
+      if exnp e then
+        check_err (fun ppf () ->
+            Fmt.pf ppf "%t%a %s: got %s." (pp_location ?here ?pos) Pp.tag `Fail
+              msg (Printexc.to_string e))
+
 let skip () = raise Core.Skip
 let () = at_exit (Format.pp_print_flush Format.err_formatter)

src/alcotest-engine/test.mli

@@ -150,6 +150,10 @@ val failf : (('a, Format.formatter, unit, 'b) format4 -> 'a) extra_info
 val check_raises : (string -> exn -> (unit -> unit) -> unit) extra_info
 (** Check that an exception is raised. *)
 
+val match_raises :
+  (string -> (exn -> bool) -> (unit -> unit) -> unit) extra_info
+(** Check that an exception is raised. *)
+
 val skip : unit -> 'a
 (** Skip the current test case.