feat(naming): the language table

Maps strings to strings and nothing else -- no calendars, no dates, no
filesystem. That is what lets every command use it without the kernel
learning about presentation.

Every lookup is total, and a miss returns THE KEY rather than the empty
string. A partial translation is therefore usable from its first line,
and the fully-degraded case is exactly today's output (bare slugs) rather
than a blank page.

--raw is a real identity table, not a special case threaded through every
call site: one value the whole program passes around.

Reuses Overlay_ini's INI reader rather than growing a second one that
would drift in its comment, quoting and trimming rules; parse_sections is
exposed in the .mli for that, with no behaviour change.

Fixes one defect found while running the brief's own tests rather than
transcribing them blind: weekday's internal lookup key is an English
day-name word (month's is already the numeral string), so on a miss it
echoed that word instead of the documented numeral, breaking both the
0=Sunday convention and Lang.raw's own identity contract for weekday.
weekday/month now fall back to string_of_int n directly on a miss
instead of through get's generic echo-the-search-key path; month is
byte-identical since its key already equals string_of_int n.

1 files changed, 85 insertions, 0 deletions

diff --git a/test/test_lang.ml b/test/test_lang.ml
new file mode 100644
index 0000000..0b16b30
--- /dev/null
+++ b/test/test_lang.ml
@@ -0,0 +1,85 @@
+module L = Colitur_naming.Lang
+
+let ok = function Ok x -> x | Error e -> Alcotest.failf "parse: %s" e
+
+let sample =
+  "[meta]\n\
+   lang = xx\n\
+   fallback = la\n\
+   [celebration]\n\
+   ef-lent-3-monday = Feria II hebdomadae III Quadragesimae\n\
+   francis-de-sales = S. Francisci Salesii\n\
+   [weekday]\n\
+   sunday = Dominica\n\
+   monday = Feria II\n\
+   [month]\n\
+   1 = Ianuarius\n\
+   [season]\n\
+   lent = Quadragesima\n\
+   [rank]\n\
+   class-1 = I classis\n\
+   [colour]\n\
+   white = albus\n\
+   [term]\n\
+   epistle = Epistola\n"
+
+let test_meta () =
+  let t = ok (L.of_string sample) in
+  Alcotest.(check string) "code" "xx" (L.code t);
+  Alcotest.(check (option string)) "fallback" (Some "la") (L.fallback_code t)
+
+let test_lookups () =
+  let t = ok (L.of_string sample) in
+  Alcotest.(check string) "celebration" "Feria II hebdomadae III Quadragesimae"
+    (L.celebration t "ef-lent-3-monday");
+  Alcotest.(check string) "weekday 0 is Sunday" "Dominica" (L.weekday t 0);
+  Alcotest.(check string) "month 1" "Ianuarius" (L.month t 1);
+  Alcotest.(check string) "season" "Quadragesima" (L.season t "lent");
+  Alcotest.(check string) "rank" "I classis" (L.rank t "class-1");
+  Alcotest.(check string) "colour" "albus" (L.colour t "white");
+  Alcotest.(check string) "term" "Epistola" (L.term t "epistle")
+
+(* THE load-bearing property: a missing key degrades to the key itself, never to
+   empty. A partial translation must be usable from its first line, and an
+   untranslated day must still say something a reader can act on. *)
+let test_missing_degrades_to_key () =
+  let t = ok (L.of_string sample) in
+  Alcotest.(check string) "unknown celebration" "ef-advent-1-monday"
+    (L.celebration t "ef-advent-1-monday");
+  Alcotest.(check string) "unknown colour" "rose" (L.colour t "rose");
+  Alcotest.(check string) "unknown term" "gospel" (L.term t "gospel")
+
+let test_fallback_chain () =
+  let base = ok (L.of_string "[meta]\nlang = la\n[celebration]\na = ALPHA\nb = BETA\n") in
+  let over = ok (L.of_string "[meta]\nlang = xx\nfallback = la\n[celebration]\nb = BETA-XX\n") in
+  let t = L.with_fallback over base in
+  Alcotest.(check string) "own key wins" "BETA-XX" (L.celebration t "b");
+  Alcotest.(check string) "falls back" "ALPHA" (L.celebration t "a");
+  Alcotest.(check string) "neither: the key" "c" (L.celebration t "c")
+
+(* --raw must be a real identity table, not a special case threaded through every
+   call site: one table the whole program can pass around. *)
+let test_raw_is_identity () =
+  Alcotest.(check string) "celebration" "ef-epiphany" (L.celebration L.raw "ef-epiphany");
+  Alcotest.(check string) "colour" "white" (L.colour L.raw "white");
+  Alcotest.(check string) "weekday" "0" (L.weekday L.raw 0)
+
+let test_malformed_is_error_not_crash () =
+  match L.of_string "[celebration\nbroken" with
+  | Error _ -> ()
+  | Ok _ -> Alcotest.fail "a malformed language file must be an Error, never accepted"
+
+let test_missing_meta_lang_is_error () =
+  match L.of_string "[celebration]\na = B\n" with
+  | Error _ -> ()
+  | Ok _ -> Alcotest.fail "a language file with no [meta] lang must be an Error"
+
+let suite =
+  ( "Lang",
+    [ Alcotest.test_case "meta" `Quick test_meta;
+      Alcotest.test_case "lookups" `Quick test_lookups;
+      Alcotest.test_case "missing degrades to key" `Quick test_missing_degrades_to_key;
+      Alcotest.test_case "fallback chain" `Quick test_fallback_chain;
+      Alcotest.test_case "raw is identity" `Quick test_raw_is_identity;
+      Alcotest.test_case "malformed is error" `Quick test_malformed_is_error_not_crash;
+      Alcotest.test_case "missing meta lang is error" `Quick test_missing_meta_lang_is_error ] )