dream: multipart/form-data parsing + 9 tests

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

lib/dream/tests/form.sx

@@ -1,4 +1,4 @@
-;; lib/dream/tests/form.sx — urlencoded parsing, Ok/Err, CSRF accept/reject.
+;; lib/dream/tests/form.sx — urlencoded parsing, Ok/Err, CSRF accept/reject, multipart.
 
 (define dream-fo-pass 0)
 (define dream-fo-fail 0)
@@ -100,14 +100,12 @@
 (define dream-fo-backend (dream-memory-sessions))
 (define dream-fo-sid (dream-fo-backend {:op "session/create"}))   ;; s1
 
-;; build a request already carrying the session cookie + csrf middleware applied
 (define
   dream-fo-stack
   (fn
     (handler)
     ((dream-sessions dream-fo-backend) ((dream-csrf "topsecret") handler))))
 
-;; a handler that emits its csrf tag
 (define
   dream-fo-tag-out
   (dream-resp-body
@@ -122,7 +120,6 @@
   (contains? dream-fo-tag-out "name=\"dream.csrf\"")
   true)
 
-;; valid token (signed for s1) -> dream-form Ok
 (define
   dream-fo-good-token
   (dr/csrf-make-token dream-csrf-sign-default "topsecret" "s1"))
@@ -178,4 +175,52 @@
         (str "dream.csrf=" dream-fo-good-token))))
   "reached")
 
+;; ── multipart/form-data ────────────────────────────────────────────
+(define
+  dream-fo-mp-body
+  (str
+    "--B1\r\n"
+    "Content-Disposition: form-data; name=\"title\"\r\n\r\n"
+    "Hello\r\n"
+    "--B1\r\n"
+    "Content-Disposition: form-data; name=\"file\"; filename=\"a.txt\"\r\nContent-Type: text/plain\r\n\r\n"
+    "line1\r\nline2\r\n"
+    "--B1--\r\n"))
+(define
+  dream-fo-mp-req
+  (dream-request "POST" "/upload" {:Content-Type "multipart/form-data; boundary=B1"} dream-fo-mp-body))
+(define dream-fo-mp (dream-multipart dream-fo-mp-req))
+(dream-fo-test "multipart is Ok" (dream-ok? dream-fo-mp) true)
+(define dream-fo-parts (dream-ok-value dream-fo-mp))
+(dream-fo-test "two parts" (len dream-fo-parts) 2)
+(dream-fo-test
+  "field value"
+  (dream-multipart-field dream-fo-parts "title")
+  "Hello")
+(dream-fo-test
+  "file part filename"
+  (get (dream-multipart-file dream-fo-parts "file") :filename)
+  "a.txt")
+(dream-fo-test
+  "file content-type"
+  (get (dream-multipart-file dream-fo-parts "file") :content-type)
+  "text/plain")
+(dream-fo-test
+  "file content keeps inner CRLF"
+  (get (dream-multipart-file dream-fo-parts "file") :content)
+  "line1\r\nline2")
+(dream-fo-test
+  "field is not a file"
+  (get (dream-multipart-file dream-fo-parts "title") :filename)
+  nil)
+(dream-fo-test
+  "non-multipart is Err"
+  (dream-err? (dream-multipart (dream-request "POST" "/x" {:Content-Type "text/plain"} "hi")))
+  true)
+(dream-fo-test
+  "quoted boundary parsed"
+  (dream-ok?
+    (dream-multipart (dream-request "POST" "/u" {:Content-Type "multipart/form-data; boundary=\"B1\""} dream-fo-mp-body)))
+  true)
+
 (define dream-fo-tests-run! (fn () {:total (+ dream-fo-pass dream-fo-fail) :passed dream-fo-pass :failed dream-fo-fail :fails dream-fo-fails}))