+
+;;;; Bugs, found by PFD
+;;; NIL parameter for ~^ means `not supplied'
+(loop for (format arg result) in
+ '(("~:{~D~v^~D~}" ((3 1 4) (1 0 2) (7 nil) (5 nil 6)) "341756")
+ ("~:{~1,2,v^~A~}" ((nil 0) (3 1) (0 2)) "02"))
+ do (assert (string= (funcall #'format nil format arg) result))
+ do (assert (string= (with-output-to-string (s)
+ (funcall (eval `(formatter ,format)) s arg))
+ result)))
+
+;;; NIL first parameter for ~R is equivalent to no parameter.
+(assert (string= (format nil "~VR" nil 5) "five"))
+(assert (string= (format nil (formatter "~VR") nil 6) "six"))
+
+;;; CSR inserted a bug into Burger & Dybvig's float printer. Caught
+;;; by Raymond Toy
+(assert (string= (format nil "~E" 1d23) "1.0d+23"))
+
+;;; Fixed-format bugs from CLISP's test suite (reported by Bruno
+;;; Haible, bug 317)
+(assert (string= (format nil "~1F" 10) "10."))
+(assert (string= (format nil "~0F" 10) "10."))
+(assert (string= (format nil "~2F" 1234567.1) "1234567."))
+
+;;; here's one that seems to fail most places. I think this is right,
+;;; and most of the other answers I've seen are definitely wrong.
+(assert (string= (format nil "~G" 1d23) "100000000000000000000000. "))
+
+;;; Adam Warner's test case
+(assert (string= (format nil "~@F" 1.23) "+1.23"))
+