Warn if the same with-kept is used more than once

src/reagent/ratom.clj

@@ -32,6 +32,14 @@
                             [body nil]))]
     `(let [destroy-obj# (cljs.core/js-obj)
            ~v (reagent.ratom/get-cached-values (quote ~v) destroy-obj#)]
+       (when *assert*
+         (when-some [c# reagent.ratom/*ratom-context*]
+           (when (== (.-ratomGeneration c#)
+                     (.-generation ~v))
+             (js/console.error
+              "The same with-kept is being used more than once in the
+              same reactive context."))
+           (set! (.-generation ~v) (.-ratomGeneration c#))))
        (let ~bs
          (let [destroy# ~destroy
                res# (do ~@forms)]

src/reagent/ratom.cljs

@@ -11,6 +11,7 @@
 
 (defonce ^boolean debug false)
 (defonce ^boolean silent false)
+(defonce generation 0)
 
 (defonce -running (clojure.core/atom 0))
 
@@ -18,6 +19,9 @@
 
 (defn capture-derefed [f obj]
   (set! (.-cljsCaptured obj) nil)
+  (when (dev?)
+    (set! (.-ratomGeneration obj)
+          (set! generation (inc generation))))
   (binding [*ratom-context* obj]
     (f)))
 
@@ -500,6 +504,9 @@
     (when-not (nil? derefed)
       (warn "using derefed is deprecated"))
     (when-not (nil? derefs)
+      (when (dev?)
+        (set! (.-ratomGeneration reaction)
+              (.-ratomGeneration derefs)))
       (-update-watching reaction derefs))
     reaction))
 

test/reagenttest/testtrack.cljs

@@ -43,6 +43,7 @@
     (is (= (running) runs))))
 
 (deftest test-track!
+  (sync)
   (let [runs (running)
         start (rv/atom 0)
         svf (fn [] @start)