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syntax-color/lexer-contract: make random-test failure declare itself

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Random tests that are implciitly injected into a program should
declare themselves as such when they fail. Otherwise, random
crashes are really confusing.
This commit is contained in:
Matthew Flatt 2014-10-20 14:18:08 -05:00
parent 66729a4473
commit a1bac35b60
1 changed files with 41 additions and 26 deletions
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67
pkgs/syntax-color-pkgs/syntax-color-lib/syntax-color/lexer-contract.rkt
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@ -33,32 +33,47 @@
(define-values (txt type paren start end) (lexer in))
(values txt type paren start end 0 #f))]
[else lexer]))
(for ([x (in-range 10)])
(define size (random 100))
(define (quash-backslash-r c)
;; it isn't clear the spec is right in
;; the case of \r\n combinations, so we
;; punt for now
(if (equal? c #\return) #\newline c))
(define s (build-string
size
(λ (c)
(quash-backslash-r
(case (random 3)
[(0)
(define s " ()@{}\"λΣ\0")
(string-ref s (random (string-length s)))]
[(1 2)
(integer->char (random 255))])))))
(define in (open-input-string s))
(port-count-lines! in)
(let loop ([mode #f][offset 0])
(define-values (txt type paren start end backup new-mode)
(3ary-lexer in offset mode))
(cond
[(equal? type 'eof) #t]
[(< end size) (loop new-mode end)]
[else #f]))))
(define initial-state (pseudo-random-generator->vector
(current-pseudo-random-generator)))
(with-handlers ([exn:fail?
(lambda (exn)
(raise
(make-exn
(format (string-append "try-some-random-streams:"
" random testing of lexer failed\n"
" lexer: ~e\n"
" pseudo-random state: ~s\n"
" error message: ~s")
lexer
initial-state
(exn-message exn))
(exn-continuation-marks exn))))])
(for ([x (in-range 10)])
(define size (random 100))
(define (quash-backslash-r c)
;; it isn't clear the spec is right in
;; the case of \r\n combinations, so we
;; punt for now
(if (equal? c #\return) #\newline c))
(define s (build-string
size
(λ (c)
(quash-backslash-r
(case (random 3)
[(0)
(define s " ()@{}\"λΣ\0")
(string-ref s (random (string-length s)))]
[(1 2)
(integer->char (random 255))])))))
(define in (open-input-string s))
(port-count-lines! in)
(let loop ([mode #f][offset 0])
(define-values (txt type paren start end backup new-mode)
(3ary-lexer in offset mode))
(cond
[(equal? type 'eof) #t]
[(< end size) (loop new-mode end)]
[else #f])))))
(define (end/c start type)
(cond