(test (string= "a~a" (format nil "a~~a")))
-(test (string= "a\na" (format nil "a~%a")))
+(test (string= "a
+a" (format nil "a~%a")))
+
+(test (string= "this is foo" (format nil "this is ~a" "foo")))
+
+(test (string= "this is \"foo\"" (format nil "this is ~S" "foo")))