the exception handling in check-equal? catches exn:break? exceptions and it probably shouldn't

[rfindler]

I think that exn:break? exceptions should not be caught by rackunit's exception handling mechanism. They shouldn't count as a failed test due to an error, they should just be unhandled as a break by the program. Below is an example program (that can be turned into a test case by, say, catching stderr) that, IMO, should behave differently.

#lang racket

(require rackunit)

(define s (make-semaphore))
(define t
  (thread
   (λ ()
     (check-equal? (let ()
                     (semaphore-post s)
                     (semaphore-wait (make-semaphore 0)))
                   5))))
(semaphore-wait s)
(break-thread t)

[AlexKnauth]

I think this is caused by default-check-around's use of (with-handlers ([(λ (_) #t) ....]) ....) in rackunit/private/check line 70

rackunit/rackunit-lib/rackunit/private/check.rkt

Line 70 in ce0ba9f

(with-handlers ([(λ (_) #t) log-and-handle!])

And possibly other with-handlers catch-all clauses in other implementations of check-around functions or test-case-around functions that catch exceptions like this.

[rfindler]

(In case it wasn't clear, I think that should be exn:fail? not the constant true function.)