add `check-txexprs-equal?`

main.rkt

@@ -341,3 +341,18 @@
                                       (make-txexpr (get-tag x) (get-attrs x) (map ->cdata (get-elements x)))
                                       (make-txexpr (get-tag x) (get-attrs x) (map loop (get-elements x))))]
                      [else x]))))
+
+(require rackunit)
+(provide+safe check-txexprs-equal?)
+(define-simple-check (check-txexprs-equal? tx1 tx2)
+  ;; txexprs are deemed equal if they differ only in the ordering of attributes.
+  ;; therefore, to check them, 1) sort their attributes, 2) straight list comparison.
+  (define symbol<? (λ syms (apply string<? (map symbol->string syms))))
+  (define (sort-attrs x)
+    (if (txexpr? x)
+        (let-values ([(tag attr elements) (txexpr->values x)])
+          (make-txexpr tag (sort attr #:key car symbol<?) (map sort-attrs elements)))
+        x))
+  (equal? (sort-attrs tx1) (sort-attrs tx2)))
+
+(check-txexprs-equal? '(p ((b "foo")(a "bar")) (span ((d "foo")(c "bar")))) '(p ((a "bar")(b "foo")) (span ((c "bar")(d "foo")))))

scribblings/txexpr.scrbl

@@ -3,10 +3,10 @@
 @; for documentation purposes, use the xexpr? from xml.
 @; the one in txexpr is just to patch over an issue with
 @; `valid-char?` in Racket 6.
-@(require scribble/eval (for-label racket txexpr xml))
+@(require scribble/eval (for-label racket txexpr xml rackunit))
 
 @(define my-eval (make-base-eval))
-@(my-eval `(require txexpr xml))
+@(my-eval `(require txexpr xml rackunit))
 
 
 @title{txexpr: Tagged X-expressions}
@@ -516,6 +516,33 @@ Ordinarily, the result of the split operation is to remove the elements that mat
 ]
 
 
+@defproc[
+(check-txexprs-equal?
+[tx1 txexpr?]
+[tx2 txexpr?])
+void?]
+Designed to be used with @racketmodname[rackunit]. Check whether @racket[_tx1] and @racket[_tx2] are @racket[equal?] except for ordering of attributes (which ordinarily has no semantic significance). Return @racket[void] if so, otherwise raise a check failure.
+
+@examples[#:eval my-eval
+(define tx1 '(div ((attr-a "foo")(attr-z "bar"))))
+(define tx2 '(div ((attr-z "bar")(attr-a "foo"))))
+(parameterize ([current-check-handler (λ _ (display "not "))])
+  (display "txexprs are ")
+  (check-txexprs-equal? tx1 tx2)
+  (displayln "equal"))
+]
+
+If ordering of attributes is relevant to your test, then just use @racket[check-equal?] as usual.
+
+@examples[#:eval my-eval
+(define tx1 '(div ((attr-a "foo")(attr-z "bar"))))
+(define tx2 '(div ((attr-z "bar")(attr-a "foo"))))
+(parameterize ([current-check-handler (λ _ (display "not "))])
+  (display "txexprs are ")
+  (check-equal? tx1 tx2)
+  (displayln "equal"))
+]
+
 
 @section{License & source code}