;; lists-ext tests — lists:sort/1, lists:sort/2, lists:usort/1.
;; Each case evaluates an Erlang expression that reduces to the bool
;; atom `true` (via =:= on the sorted result) and checks its name.

(define er-lx-test-count 0)
(define er-lx-test-pass 0)
(define er-lx-test-fails (list))

(define
  er-lx-test
  (fn
    (name actual expected)
    (set! er-lx-test-count (+ er-lx-test-count 1))
    (if
      (= actual expected)
      (set! er-lx-test-pass (+ er-lx-test-pass 1))
      (append! er-lx-test-fails {:name name :expected expected :actual actual}))))

;; eval an Erlang source string and return the result atom's name
(define er-lx-nm (fn (src) (get (erlang-eval-ast src) :name)))

;; ── lists:sort/1 ──────────────────────────────────────────────────
(er-lx-test "sort/1 ascending"
  (er-lx-nm "lists:sort([3,1,2]) =:= [1,2,3]") "true")

(er-lx-test "sort/1 already sorted"
  (er-lx-nm "lists:sort([1,2,3]) =:= [1,2,3]") "true")

(er-lx-test "sort/1 empty"
  (er-lx-nm "lists:sort([]) =:= []") "true")

(er-lx-test "sort/1 singleton"
  (er-lx-nm "lists:sort([7]) =:= [7]") "true")

(er-lx-test "sort/1 keeps duplicates"
  (er-lx-nm "lists:sort([3,1,2,1]) =:= [1,1,2,3]") "true")

(er-lx-test "sort/1 length preserved"
  (erlang-eval-ast "length(lists:sort([5,4,3,2,1]))") 5)

(er-lx-test "sort/1 term order: number < atom"
  (er-lx-nm "lists:sort([b,a,1]) =:= [1,a,b]") "true")

(er-lx-test "sort/1 tuples elementwise"
  (er-lx-nm "lists:sort([{2,a},{1,b},{1,a}]) =:= [{1,a},{1,b},{2,a}]") "true")

;; ── lists:sort/2 ──────────────────────────────────────────────────
(er-lx-test "sort/2 ascending =<"
  (er-lx-nm "lists:sort(fun(A,B) -> A =< B end, [3,1,2]) =:= [1,2,3]") "true")

(er-lx-test "sort/2 descending >="
  (er-lx-nm "lists:sort(fun(A,B) -> A >= B end, [1,3,2]) =:= [3,2,1]") "true")

(er-lx-test "sort/2 stable on equal keys"
  (er-lx-nm
    "lists:sort(fun({A,_},{B,_}) -> A =< B end, [{1,x},{1,y},{0,z}]) =:= [{0,z},{1,x},{1,y}]")
  "true")

(er-lx-test "sort/2 empty"
  (er-lx-nm "lists:sort(fun(A,B) -> A =< B end, []) =:= []") "true")

;; ── lists:usort/1 ─────────────────────────────────────────────────
(er-lx-test "usort/1 removes duplicates"
  (er-lx-nm "lists:usort([3,1,2,1,3]) =:= [1,2,3]") "true")

(er-lx-test "usort/1 empty"
  (er-lx-nm "lists:usort([]) =:= []") "true")

(er-lx-test "usort/1 all equal collapses to one"
  (er-lx-nm "lists:usort([5,5,5]) =:= [5]") "true")

(er-lx-test "usort/1 already unique"
  (er-lx-nm "lists:usort([1,2,3]) =:= [1,2,3]") "true")

(er-lx-test "usort/1 length after dedup"
  (erlang-eval-ast "length(lists:usort([4,4,2,2,1,1,4]))") 3)