dream: flash messages — single-request cookie store + 14 tests

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/dream/tests/flash.sx

@@ -0,0 +1,129 @@
+;; lib/dream/tests/flash.sx — codec + read-after-write across requests.
+
+(define dream-fl-pass 0)
+(define dream-fl-fail 0)
+(define dream-fl-fails (list))
+
+(define
+  dream-fl-test
+  (fn
+    (name actual expected)
+    (if
+      (= actual expected)
+      (set! dream-fl-pass (+ dream-fl-pass 1))
+      (begin
+        (set! dream-fl-fail (+ dream-fl-fail 1))
+        (append! dream-fl-fails {:name name :actual actual :expected expected})))))
+
+;; ── codec ──────────────────────────────────────────────────────────
+(dream-fl-test "encode one" (dr/flash-encode (list {:message "saved" :category "info"})) "info|saved")
+(dream-fl-test
+  "encode two"
+  (dr/flash-encode (list {:message "a" :category "info"} {:message "b" :category "error"}))
+  "info|a~error|b")
+(dream-fl-test "decode one" (dr/flash-decode "info|saved") (list {:message "saved" :category "info"}))
+(dream-fl-test "decode empty" (dr/flash-decode "") (list))
+(dream-fl-test
+  "roundtrip special chars"
+  (dr/flash-decode (dr/flash-encode (list {:message "a~b%c" :category "x|y"})))
+  (list {:message "a~b%c" :category "x|y"}))
+(dream-fl-test "escape pipe" (dr/flash-encode (list {:message "a|b" :category "c"})) "c|a%7Cb")
+
+;; extract a cookie value from a Set-Cookie string
+(define
+  dream-fl-cookie-val
+  (fn
+    (setc)
+    (let
+      ((after (substr setc (+ (index-of setc "=") 1))))
+      (substr after 0 (index-of after ";")))))
+
+;; ── read-after-write across requests ───────────────────────────────
+(define
+  dream-fl-set-h
+  (fn
+    (req)
+    (begin (dream-add-flash-message req "info" "Saved!") (dream-text "done"))))
+(define dream-fl-set-app (dream-flash dream-fl-set-h))
+
+;; request 1: add a flash, no incoming -> sets the flash cookie
+(define
+  dream-fl-r1
+  (dream-fl-set-app (dream-request "POST" "/save" {} "")))
+(dream-fl-test "writer body" (dream-resp-body dream-fl-r1) "done")
+(dream-fl-test
+  "writer sets flash cookie"
+  (len (dream-resp-cookies dream-fl-r1))
+  1)
+(dream-fl-test
+  "writer has no incoming"
+  (dream-flash-messages
+    (assoc (dream-request "GET" "/" {} "") :dream-flash {:box (dr/flash-box) :incoming (list)}))
+  (list))
+
+;; request 2: carries the flash cookie -> handler reads it, cookie cleared
+(define
+  dream-fl-cval
+  (dream-fl-cookie-val (first (dream-resp-cookies dream-fl-r1))))
+(define
+  dream-fl-read-h
+  (fn
+    (req)
+    (let
+      ((msgs (dream-flash-messages req)))
+      (dream-text
+        (if (empty? msgs) "none" (dream-flash-message (first msgs)))))))
+(define dream-fl-read-app (dream-flash dream-fl-read-h))
+(define
+  dream-fl-r2
+  (dream-fl-read-app (dream-request "GET" "/" {:Cookie (str "dream.flash=" dream-fl-cval)} "")))
+(dream-fl-test "reader sees message" (dream-resp-body dream-fl-r2) "Saved!")
+(dream-fl-test
+  "reader clears cookie (Max-Age=0)"
+  (contains? (first (dream-resp-cookies dream-fl-r2)) "Max-Age=0")
+  true)
+
+;; request 3: no flash cookie -> nothing to read, no cookie set
+(define
+  dream-fl-r3
+  (dream-fl-read-app (dream-request "GET" "/" {} "")))
+(dream-fl-test "no flash -> none" (dream-resp-body dream-fl-r3) "none")
+(dream-fl-test
+  "no flash -> no cookie"
+  (len (dream-resp-cookies dream-fl-r3))
+  0)
+
+;; ── multiple categories ────────────────────────────────────────────
+(define
+  dream-fl-multi-h
+  (fn
+    (req)
+    (begin
+      (dream-add-flash-message req "info" "i1")
+      (dream-add-flash-message req "error" "e1")
+      (dream-add-flash-message req "info" "i2")
+      (dream-text "ok"))))
+(define
+  dream-fl-multi-r1
+  ((dream-flash dream-fl-multi-h) (dream-request "GET" "/" {} "")))
+(define
+  dream-fl-multi-val
+  (dream-fl-cookie-val (first (dream-resp-cookies dream-fl-multi-r1))))
+(define
+  dream-fl-count-h
+  (fn
+    (req)
+    (dream-text
+      (str
+        (len (dream-flash-messages req))
+        "/"
+        (len (dream-flash-of req "info"))))))
+(define
+  dream-fl-multi-r2
+  ((dream-flash dream-fl-count-h) (dream-request "GET" "/" {:Cookie (str "dream.flash=" dream-fl-multi-val)} "")))
+(dream-fl-test
+  "multi: all + filtered counts"
+  (dream-resp-body dream-fl-multi-r2)
+  "3/2")
+
+(define dream-fl-tests-run! (fn () {:total (+ dream-fl-pass dream-fl-fail) :passed dream-fl-pass :failed dream-fl-fail :fails dream-fl-fails}))