Wire_diffSourceDifferential testing: one Wire.Codec.t against external C behaviour.
A diff test keeps the codec as the single OCaml authority and compares it against C read/write functions, typically backed by EverParse-generated code.
type t = {name : string;wire_size : int;test_read : string -> result;test_write : string -> result;test_roundtrip : string -> result;}A type-erased diff test.
val harness :
name:string ->
codec:'r Wire.Codec.t ->
read:(string -> 'a option) ->
write:('a -> string option) ->
project:('r -> 'a) ->
equal:('a -> 'a -> bool) ->
?ocaml_read:(string -> 'a option) ->
unit ->
tharness ~name ~codec ~read ~write ~project ~equal ?ocaml_read () creates a diff test comparing an OCaml codec against external read/write functions.
The test compares both implementations in a single semantic domain 'a: project maps OCaml-decoded values into that domain, read extracts an external value from wire bytes, and write serializes a value in that same domain back to wire bytes. ocaml_read, when provided, overrides the default OCaml byte-reading path derived from codec and project.