dream: CORS middleware + preflight handling + 12 tests

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

lib/dream/tests/cors.sx

@@ -0,0 +1,93 @@
+;; lib/dream/tests/cors.sx — CORS decoration + preflight.
+
+(define dream-co-pass 0)
+(define dream-co-fail 0)
+(define dream-co-fails (list))
+
+(define
+  dream-co-test
+  (fn
+    (name actual expected)
+    (if
+      (= actual expected)
+      (set! dream-co-pass (+ dream-co-pass 1))
+      (begin
+        (set! dream-co-fail (+ dream-co-fail 1))
+        (append! dream-co-fails {:name name :actual actual :expected expected})))))
+
+(define dream-co-h (fn (req) (dream-text "payload")))
+(define dream-co-app (dream-cors dream-co-h))
+
+;; ── decoration of normal responses ─────────────────────────────────
+(define dream-co-get (dream-co-app (dream-request "GET" "/" {} "")))
+(dream-co-test
+  "allow-origin star"
+  (dream-resp-header dream-co-get "access-control-allow-origin")
+  "*")
+(dream-co-test "body preserved" (dream-resp-body dream-co-get) "payload")
+(dream-co-test "status preserved" (dream-status dream-co-get) 200)
+(dream-co-test
+  "no credentials by default"
+  (dream-resp-header dream-co-get "access-control-allow-credentials")
+  nil)
+
+;; ── preflight OPTIONS ──────────────────────────────────────────────
+(define
+  dream-co-pre
+  (dream-co-app (dream-request "OPTIONS" "/" {} "")))
+(dream-co-test "preflight 204" (dream-status dream-co-pre) 204)
+(dream-co-test
+  "preflight origin"
+  (dream-resp-header dream-co-pre "access-control-allow-origin")
+  "*")
+(dream-co-test
+  "preflight methods"
+  (contains?
+    (dream-resp-header dream-co-pre "access-control-allow-methods")
+    "POST")
+  true)
+(dream-co-test
+  "preflight headers"
+  (dream-resp-header dream-co-pre "access-control-allow-headers")
+  "Content-Type")
+(dream-co-test
+  "preflight max-age"
+  (dream-resp-header dream-co-pre "access-control-max-age")
+  "86400")
+
+;; ── custom origin ──────────────────────────────────────────────────
+(define
+  dream-co-custom
+  ((dream-cors-origin "https://app.example.com") dream-co-h))
+(dream-co-test
+  "custom origin"
+  (dream-resp-header
+    (dream-co-custom (dream-request "GET" "/" {} ""))
+    "access-control-allow-origin")
+  "https://app.example.com")
+
+;; ── credentials enabled ────────────────────────────────────────────
+(define
+  dream-co-cred
+  ((dream-cors-with (assoc dream-cors-defaults :credentials true))
+    dream-co-h))
+(dream-co-test
+  "credentials header"
+  (dream-resp-header
+    (dream-co-cred (dream-request "GET" "/" {} ""))
+    "access-control-allow-credentials")
+  "true")
+
+;; ── composes around a router ───────────────────────────────────────
+(define
+  dream-co-router
+  (dream-cors
+    (dream-router (list (dream-get "/api" (fn (req) (dream-json "{}")))))))
+(dream-co-test
+  "router cors origin"
+  (dream-resp-header
+    (dream-co-router (dream-request "GET" "/api" {} ""))
+    "access-control-allow-origin")
+  "*")
+
+(define dream-co-tests-run! (fn () {:total (+ dream-co-pass dream-co-fail) :passed dream-co-pass :failed dream-co-fail :fails dream-co-fails}))