4.1 Testing Printed Output🔗ℹ

Use expect when the behavior you care about is what the code prints:

#:lang at-exp racket

(require recspecs)

(define (greet name)

(printf "Hello, ~a!\n" name))

(expect (greet "Ada")

"Hello, Ada!")

4.2 Testing Printed Values🔗ℹ

Use expect/print when you want to test the value an expression returns. Recspecs prints the value with print before comparing it:

#:lang at-exp racket

(require recspecs)

(expect/print (map string-upcase '("red" "blue"))

"'(\"RED\" \"BLUE\")")

Use expect/pretty for data that is easier to inspect with pretty-print:

#:lang at-exp racket

(require recspecs)

(expect/pretty '(shopping-list

(item "apples" #:qty 2 #:aisle "produce")

(item "bread" #:qty 1 #:aisle "bakery")

(item "coffee" #:qty 1 #:aisle "dry goods"))

"'(shopping-list""\n""  "

"(item \"apples\" #:qty 2 #:aisle \"produce\")""\n""  "

"(item \"bread\" #:qty 1 #:aisle \"bakery\")""\n""  "

"(item \"coffee\" #:qty 1 #:aisle \"dry goods\"))")

4.3 Testing Error Messages🔗ℹ

Use expect-exn when the expected behavior is an exception:

#:lang at-exp racket

(require recspecs)

(define (parse-port n)

(unless (and (integer? n) (<= 0 n 65535))

(raise-user-error 'parse-port "expected an integer from 0 to 65535"))

n)

(expect-exn (parse-port 70000)

"parse-port: expected an integer from 0 to 65535")

4.4 Capturing Output Without an Expectation🔗ℹ

Use capture-output when you need the printed text as a string for some other assertion or helper:

(require recspecs rackunit)

(define out

(capture-output

(lambda ()

(display "ready"))))

(check-equal? out "ready")