How to require inside a Racket macro? - racket

Question

I currently am putting unit tests at the bottom of the file I'm working on, like this:
(provide foo)
(define (bar x) (+ 1 x))
;; unit tests
(module+ test
(require racket/pretty)
(define testcases '(2 3 4))
(for ([test testcases])
(pretty-print (bar test))))
This works, but I want to avoid repeating the boilerplate unit test code for all my modules. Having never written a macro in Racket before, I'm unsure how to get the various parts to fit together.
I would like to have the following code expand to the boilerplate version above:
(provide foo)
(define (bar x) (+ 1 x))
;; unit tests
(test foo '(2 3 4))

Answer 1

For the test macro, are you sure you need to generate a require from the macro? You can have the test macro generate a use of pretty-print if racket/pretty is required in the file that defines test, and then it doesn't matter whether there's a require in the file that uses test.
For example if you have two files macro.rkt and use.rkt:
file macro.rkt:
#lang racket
(provide test)
(require racket/pretty
syntax/parse/define)
(define-simple-macro (test fn:id args:expr)
(module+ test
(define testcases args)
(for ([test testcases])
(pretty-print (fn test)))))
file use.rkt:
#lang racket
(require "macro.rkt")
(provide foo)
(define (foo x) (+ 1 x))
;; unit tests
(test foo '(2 3 4))
Then the reference to pretty-print works in the output of the macro even though it's not normally available in use.rkt. It works because pretty-print gets its scope from the macro definition site, not the use site.
Does this work for your problem?