(module sample-solutions-testsuite-tp mzscheme
  (provide require-library)
  (require mzlib/include)
  
  (define-syntax require-library
    (let ([cache null])
      (lambda (stx)
        (syntax-case stx ()
          [(_ fn-stx lib-stx)
           (let ([fn (syntax-object->datum (syntax fn-stx))]
                 [lib (syntax-object->datum (syntax lib-stx))])
             (unless (equal? lib "solutions")
               (raise-syntax-error
                #f
                "expected `solutions' collection as second argument to require-library"
                stx))
             (unless (string? fn)
               (raise-syntax-error
                #f
                "expected string constant as first argument to require-library"
                stx))
             (if (member fn cache)
                 (syntax (void))
                 (with-syntax ([full-fn 
                                (bytes->string/utf-8
                                 (path->bytes
                                  (build-path 
                                   (with-handlers ([exn:fail:filesystem?
                                                    (lambda (x)
                                                      (current-load-relative-directory))])
                                     (collection-path "solutions"))
                                   fn)))]
                               [orig stx])
                   (set! cache (cons fn cache))
                   (syntax
                    (begin
                      (include-at/relative-to orig orig full-fn)
                      (void))))))])))))