Merge pull request #276 from omasanori/parameterize

Refactor t/parameterize.scm with (picrin test).

t/parameterize.scm

@@ -1,8 +1,9 @@
 (import (scheme base)
-        (scheme write))
+        (picrin test))
 
-; expects "piece by piece by piece.\n"
-(write
+(test-begin)
+
+(test "piece by piece by piece.\n"
       (parameterize
           ((current-output-port (open-output-string)))
         (display "piece")
@@ -10,3 +11,5 @@
         (display "by piece.")
         (newline)
         (get-output-string)))
+
+(test-end)