test(tests/lean): new simplifier test

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>

tests/lean/simp27.lean

@@ -0,0 +1,13 @@
+rewrite_set simple
+add_rewrite eq_id imp_truel imp_truer Nat::add_zeror : simple
+variables a b : Nat
+variable  f : (Nat → Nat) → Nat
+variable  g : Nat → Nat
+
+(*
+local t = parse_lean('λ x x2, (∀ y, g y = x) → g (a + x + b) > x2 + g x')
+local t2, pr = simplify(t, "simple")
+print(t2)
+print(pr)
+get_environment():type_check(pr)
+*)

tests/lean/simp27.lean.expected.out

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+  Set: pp::colors
+  Set: pp::unicode
+  Assumed: a
+  Assumed: b
+  Assumed: f
+  Assumed: g
+λ x x2 : ℕ, (∀ y : ℕ, g y = x) → x > x2 + x
+funext (λ x : ℕ,
+          funext (λ x2 : ℕ,
+                    imp_congr
+                        (refl (∀ y : ℕ, g y = x))
+                        (λ C::3 : ∀ y : ℕ, g y = x,
+                           congr (congr2 Nat::gt (C::3 (a + x + b))) (congr2 (Nat::add x2) (C::3 x)))))