kernels: Make "kernel_info_request" test more robust.

* tests/kernels.scm ("kernel_info_request"): Rewrite to remove assumptions
about ordering, and to account for all the replies.

tests/kernels.scm

@@ -59,31 +59,39 @@
   (let ((request (message (header "kernel_info_request" "luser" "12345")
                           "{}")))
     (send-message %kernel request)
-    (let* ((reply1  (read-message %kernel))
-           (reply2  (read-message %kernel))
-           (reply3  (read-message %kernel))
-           (replies (pk 'replies (list reply1 reply2 reply3))))
-      (and (every message? replies)
-
-           (string=? "status" (message-type reply1))
-           (string=? "busy"
-                     (assoc-ref (json-string->scm (message-content reply1))
-                                "execution_state"))
-           (equal? (message-parent-header reply1) (message-header request))
-
-           (string=? "kernel_info_reply" (message-type reply2))
-           (equal? (message-parent-header reply2) (message-header request))
-
-           (string=? "status" (message-type reply3))
-           (string=? "idle"
-                     (assoc-ref (json-string->scm (message-content reply3))
-                                "execution_state"))
-           (equal? (message-parent-header reply3) (message-header request))
-
-           (assoc-ref (assoc-ref
-                       (json-string->scm (message-content reply2))
-                       "language_info")
-                      "name")))))
+    (let* ((replies (unfold (cut > <> 2)
+                            (lambda (_)
+                              (read-message %kernel 10000))
+                            1+ 0)))
+      (define (type-predicate type)
+        (lambda (message)
+          (string=? (message-type message) type)))
+
+      (and (every message? (pk 'replies replies))
+
+           (match (filter (type-predicate "status") replies)
+             ((busy idle)
+              ;; We got two message: busy *then* idle.
+              (and (string=? "busy"
+                             (assoc-ref (json-string->scm
+                                         (message-content busy))
+                                        "execution_state"))
+                   (string=? "idle"
+                             (assoc-ref (json-string->scm
+                                         (message-content idle))
+                                        "execution_state"))
+                   (equal? (message-parent-header busy)
+                           (message-header request))
+                   (equal? (message-parent-header idle)
+                           (message-header request)))))
+
+           (let ((reply (find (type-predicate "kernel_info_reply")
+                              replies)))
+             (and (equal? (message-parent-header reply)
+                          (message-header request))
+                  (let* ((content  (json-string->scm (message-content reply)))
+                         (language (assoc-ref content "language_info")))
+                    (assoc-ref language "name"))))))))
 
 (unless %kernel (test-skip 1))
 (test-equal "execute_request"