Btter tests for the package index

tests/coreutils.rkt

@@ -119,7 +119,6 @@
      (check-true (regexp-match? #rx"a[/\\]b"
                                 (capture-output coreutils-dirname "a/b/c.txt")))
 
-     (define saved-env (getenv "RASH_COREUTILS_TEST"))
      (define env-output
        (parameterize ([current-coreutils-command-runner
                        (λ (command)
@@ -134,18 +133,17 @@
           'RASH_COREUTILS_VALUE)))
      (check-equal? env-output "42\n")
 
-     (dynamic-wind
-       void
-       (λ ()
-         (putenv "RASH_COREUTILS_TEST" "before")
-         (check-equal? (capture-output coreutils-printenv "RASH_COREUTILS_TEST")
-                       "before\n"))
-       (λ ()
-         (if saved-env
-             (putenv "RASH_COREUTILS_TEST" saved-env)
-             (putenv "RASH_COREUTILS_TEST" #f))))
+     (define test-environment
+       (environment-variables-copy (current-environment-variables)))
+     (environment-variables-set!
+      test-environment
+      #"RASH_COREUTILS_TEST"
+      #"before")
+     (parameterize ([current-environment-variables test-environment])
+       (check-equal? (capture-output coreutils-printenv "RASH_COREUTILS_TEST")
+                     "before\n"))
 
-     (check-true (regexp-match? #rx"[0-9]{4}-[0-9]{2}-[0-9]{2}T"
+     (check-true (regexp-match? #px"[0-9]{4}-[0-9]{2}-[0-9]{2}T"
                                 (capture-output coreutils-date "--iso")))
 
      (check-exn