I cut 'n' pasted this code

  $ cat t.scm
  ;; Initialize and give a name to a simple testsuite.
  (test-begin "vec-test")
  (define v (make-vector 5 99))
  ;; Require that an expression evaluate to true.
  (test-assert (vector? v))
  ;; Test that an expression is eqv? to some other expression.
  (test-eqv (vector-ref v 2) 99)
  (vector-set! v 2 7)
  (test-eqv (vector-ref v 2) 7)
  ;; Finish the testsuite, and report results.
  (test-end "vec-test")

  $

from http://srfi.schemers.org/srfi-64/srfi-64.html and downloaded
http://srfi.schemers.org/srfi-64/testing.scm on that page as srfi-64.scm.  Then
I ran guile on a debian testing system updated weekly and did

  $ guile
  guile> (version)
  "1.6.8"
  guile> (load "srfi-64.scm")
  guile> (load "t.scm")
  %%%% Starting test vec-test  (Writing full log to "vec-test.log")
  FAIL
  # of expected passes      2
  # of unexpected failures  1
  guile> (exit)

  $ cat vec-test.log
  %%%% Starting test vec-test
  Group begin: vec-test
  Test begin:
  Test end:
    result-kind: fail
    actual-value: #f
    expected-value: #<procedure exp (z)>
  Test begin:
  Test end:
    result-kind: pass
    actual-value: 99
    expected-value: 99
  Test begin:
  Test end:
    result-kind: pass
    actual-value: 7
    expected-value: 7
  Group end: vec-test
  # of expected passes      2
  # of unexpected failures  1

  $

I'm not understanding why the first test failed; what would be the explanation
for that?