Add a fibers-parallel test

tests/parallelism.scm

@@ -93,4 +93,22 @@
         1))
      #:unwind? #t)))
 
+(run-fibers-for-tests
+ (lambda ()
+   (let ((a 0))
+     (call-with-values
+         (lambda ()
+           (fibers-parallel
+            (begin
+              (sleep 1)
+              1)
+            (begin
+              (set! a 1)
+              2)))
+       (lambda (a b)
+         (assert-equal a 1)
+         (assert-equal b 2)))
+
+     (assert-equal a 1))))
+
 (display "parallelism test finished successfully\n")