refactor(3p/lisp/mime4cl/test): create one test case per sample file

Since rt.lisp seems to start tests in parallel, the informational output
about which sample file is being tested gets mangled in all sorts of
ways. The solution is to just loop over the sample files outside a test
and schedule a single test case per sample file from there.

Change-Id: I4494e4a526ce6d92a298cf7daf06c8013c7ca605
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8569
Reviewed-by: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI

third_party/lisp/mime4cl/test/mime.lisp

@@ -27,17 +27,15 @@
                          *load-pathname*
                          #P"")))
 
-(deftest mime.1
-    (loop
-       for f in (directory (make-pathname :defaults *samples-directory*
-                                          :name :wild
-                                          :type "msg"))
-       do
-         (format t "~A:~%" f)
-         (finish-output)
-         (let* ((orig (mime-message f))
-                (dup (mime-message (with-output-to-string (out) (encode-mime-part orig out)))))
-           (unless (mime= orig dup)
-             (return nil)))
-       finally (return t))
-  t)
+(loop
+ for f in (directory (make-pathname :defaults *samples-directory*
+                                    :name :wild
+                                    :type "msg"))
+ for i from 1
+ do
+ (add-test (intern (format nil "MIME.~A" i))
+           `(let* ((orig (mime-message ,f))
+                   (dup (mime-message
+                         (with-output-to-string (out) (encode-mime-part orig out)))))
+              (mime= orig dup))
+           t))