static-contracts: fix list-length/sc

- Change `list-length/sc` to be a contract for lists
- Add tests to check sc-generated contracts against values

typed-racket-lib/typed-racket/static-contracts/combinators/lengths.rkt

@@ -27,8 +27,7 @@
 (define (list-length/sc* n)
   (if (zero? n)
       empty-list/sc
-      empty-vector/sc))
-
+      (list-length/sc n)))
 
 (define empty-list/sc (flat/sc #'null?))
 (define empty-vector/sc (vector-length/sc 0))

typed-racket-test/unit-tests/static-contract-instantiate-tests.rkt

@@ -0,0 +1,44 @@
+#lang racket/base
+
+;; Instantiate static contracts to contracts,
+;;  check that the contracts accept/reject the right values.
+
+(require "test-utils.rkt" "evaluator.rkt"
+         rackunit
+         (for-syntax
+           syntax/parse
+           racket/base
+           (static-contracts instantiate optimize combinators)))
+
+(provide tests)
+(gen-test-main)
+
+(define-syntax sc->contract
+  (syntax-parser
+    [(_ sc:expr)
+     (syntax/loc #'e
+       (phase1-phase0-eval
+         (define defs+ctc (instantiate sc (lambda (#:reason _) (error "static-contract could not be converted to a contract"))))
+         #`(let () #,@(car defs+ctc) #,(cadr defs+ctc))))]))
+
+(define tests
+  (test-suite "Conversion Tests"
+    (let ([nat-ctc (sc->contract (flat/sc #'exact-nonnegative-integer?))])
+      (check-true (nat-ctc 4))
+      (check-false (nat-ctc -4)))
+    (let ([list-0 (sc->contract (list-length/sc 0))])
+      (check-true (list-0 '()))
+      (check-false (list-0 '#()))
+      (check-false (list-0 '(1))))
+    (let ([list-1 (sc->contract (list-length/sc 1))])
+      (check-true (list-1 '(1)))
+      (check-false (list-1 '#()))
+      (check-false (list-1 '())))
+    (let ([vector-0 (sc->contract (vector-length/sc 0))])
+      (check-true (vector-0 '#()))
+      (check-false (vector-0 '()))
+      (check-false (vector-0 '#(1))))
+    (let ([vector-1 (sc->contract (vector-length/sc 1))])
+      (check-true (vector-1 '#(1)))
+      (check-false (vector-1 '#()))
+      (check-false (vector-1 '())))))

typed-racket-test/unit-tests/static-contract-optimizer-tests.rkt

@@ -85,8 +85,6 @@
       #:neg empty-list/sc)
 
     ;; Heterogeneous Lists
-    ;; TODO fix ability to test equality here
-    #;
     (check-optimize (list/sc any/sc)
       #:pos any/sc
       #:neg (list-length/sc 1))
@@ -116,15 +114,12 @@
 
     ;; Heterogeneous Vectors
     ;; TODO fix ability to test equality here
-    #;
     (check-optimize (vector/sc any/sc)
       #:pos any/sc
       #:neg (vector-length/sc 1))
     (check-optimize (vector/sc none/sc)
       #:pos (vector/sc none/sc)
       #:neg (vector/sc none/sc))
-    ;; TODO fix ability to test equality here
-    #;
     (check-optimize (vector/sc)
       #:pos any/sc
       #:neg empty-vector/sc)