1 files changed, 60 insertions, 0 deletions
diff --git a/test/unit/karuta/Translator.ml b/test/unit/karuta/Translator.ml
new file mode 100644
index 0000000..92bd57f
--- /dev/null
+++ b/test/unit/karuta/Translator.ml
@@ -0,0 +1,60 @@
+open Rnt
+module Translator = Subsystem.Karuta.Translator
+module Gen = QCheck2.Gen
+
+let value =
+  Gen.oneof
+    [ Gen.map (fun s -> Concepts.Value.String s) Gen.string_small;
+      Gen.map
+        (fun n -> Concepts.Value.Integer n)
+        (Gen.oneof [Gen.int; Gen.oneofl [min_int; max_int]]) ]
+
+let tuple =
+  Gen.map2
+    (fun type_ attributes -> {Concepts.Tuple.type_; attributes= BatMap.String.of_list attributes})
+    Gen.string_small
+    (Gen.small_list (Gen.pair Gen.string_small value))
+
+let print tuple = tuple.Concepts.Tuple.type_ ^ " " ^ Concepts.Tuple.to_string tuple
+
+let same (a : Concepts.Tuple.t) (b : Concepts.Tuple.t) =
+  a.type_ = b.type_ && BatMap.String.equal Concepts.Value.equal a.attributes b.attributes
+
+let decodes_to_itself =
+  QCheck2.Test.make ~name:"a tuple decodes to itself" ~print tuple (fun tuple ->
+      match Translator.decode (Translator.encode tuple) with
+      | Ok decoded -> same tuple decoded
+      | Error _ -> false )
+
+let a_cut_term_is_refused =
+  QCheck2.Test.make ~name:"a cut term is refused" ~print tuple (fun tuple ->
+      let bytes = Translator.encode tuple in
+      List.init (String.length bytes) (fun n -> Translator.decode (String.sub bytes 0 n))
+      |> List.for_all Result.is_error )
+
+(* term_to_binary writes an integer that fits a byte as 97, and one that
+   fits 32 bits as 98, which encode never does *)
+let erlang_integers_decode =
+  QCheck2.Test.make ~name:"an integer as term_to_binary writes it decodes to itself"
+    ~print:string_of_int
+    (Gen.oneof [Gen.int_range 0 255; Gen.int_range (-0x8000_0000) 0x7fff_ffff])
+    (fun n ->
+      let term = Buffer.create 32 in
+      (* {<<"t">>, #{<<"n">> => n}} *)
+      Buffer.add_string term
+        "\131\104\002\109\000\000\000\001t\116\000\000\000\001\109\000\000\000\001n";
+      if n >= 0 && n < 256 then begin
+        Buffer.add_uint8 term 97; Buffer.add_uint8 term n
+      end
+      else begin
+        Buffer.add_uint8 term 98;
+        Buffer.add_int32_be term (Int32.of_int n)
+      end;
+      match Translator.decode (Buffer.contents term) with
+      | Ok {attributes; _} -> BatMap.String.bindings attributes = ["n", Concepts.Value.Integer n]
+      | Error _ -> false )
+
+let suites () =
+  [ ( "karuta/translator",
+      List.map QCheck_alcotest.to_alcotest
+        [decodes_to_itself; a_cut_term_is_refused; erlang_integers_decode] ) ]