[racket] Tests before of to define the function

[Juan Francisco Cantero Hurtado]

In Beginning Student mode I can to define a test before of the function:
(check-expect (double 2) 4)
(define (double n)
    (* n 2))

In #lang racket, the next code fails:

(require rackunit)
(check-equal? (double 2) 4)
(define (double n)
    (* n 2))

Is it possible to write the tests before of the functions in racket, 
like in BS?

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