New (failing) test case re: the approach to relaying

syndicate/test/core/nesting-confusion.rkt

@@ -0,0 +1,45 @@
+#lang imperative-syndicate/test-implementation
+;; Uhoh! The current (2018-05-02) scheme for relaying between
+;; dataspaces instantiates each pattern when a matching assertion
+;; appears and then relays the result on via an ordinary assertion.
+;; However, this is probably wrong! If one inner observer monitors
+;;
+;;     (inbound (x _ $y))
+;;
+;; while another monitors
+;;
+;;     (inbound (x $z _))
+;;
+;; then the second one will see a literal `(discard)` for `z`!
+
+(require racket/string)
+
+(assertion-struct researcher (name topic))
+
+(test-case
+    [(spawn #:name 'tony
+            (assert (researcher "Tony" "Computering"))
+            (assert (researcher "Tony" "Bicycling")))
+     (spawn #:name 'alice
+            (assert (researcher "Alice" "Cryptography"))
+            (assert (researcher "Alice" "Bicycling")))
+     (spawn #:name 'eve
+            (assert (researcher "Eve" "Cryptography"))
+            (assert (researcher "Eve" "Computering"))
+            (assert (researcher "Eve" "Evil")))
+
+     (dataspace #:name 'inner-dataspace
+                (spawn #:name 'all-topics
+                       (during (inbound (researcher _ $topic))
+                         (on-start (printf "Added topic: ~a\n" topic))
+                         (on-stop (printf "Removed topic: ~a\n" topic))))
+                (spawn #:name 'all-researchers
+                       (during (inbound (researcher $name _))
+                         (on-start (printf "Added researcher: ~a\n" name))
+                         (on-stop (printf "Removed researcher: ~a\n" name)))))]
+  no-crashes
+  (procedure-rename
+   (lambda ()
+     (not (memf (lambda (line) (string-contains? line "#s(discard)"))
+                (collected-lines))))
+   'no-mention-of-discard))