Test two ways to get regular atoms work in reactive context

src/reagent/ratom.cljs

@@ -628,3 +628,69 @@
  (flush!)))
  (dispose! res))))
  (ratom-perf))
+
+(deftype WrappedAtom [x]
+ IAtom
+ IReactiveAtom
+
+ IEquiv
+ (-equiv [o other] (identical? o other))
+
+ IDeref
+ (-deref [this]
+ (notify-deref-watcher! x)
+ @x)
+
+ IReset
+ (-reset! [a new-value]
+ (reset! x new-value))
+
+ ISwap
+ (-swap! [a f] (swap! x f))
+ (-swap! [a f x] (swap! x f x))
+ (-swap! [a f x y] (swap! x f x y))
+ (-swap! [a f x y more] (swap! x f x y more))
+
+ IWithMeta
+ (-with-meta [_ new-meta]
+ (WrappedAtom. (with-meta x new-meta)))
+
+ IMeta
+ (-meta [_] (meta x))
+
+ IPrintWithWriter
+ (-pr-writer [a w opts] (pr-atom a w opts "WrappedAtom" {:atom x}))
+
+ IWatchable
+ (-notify-watches [this old new] (-notify-watches x old new))
+ (-add-watch [this key f] (-add-watch x key f))
+ (-remove-watch [this key] (-remove-watch x key))
+
+ IHash
+ (-hash [this] (goog/getUid this)))
+
+(defn ->ratom
+ "Wraps Atom like object so that it notifies current reactive context
+ on deref.
+
+ The object must implement be a cljs.core.Atom or
+ implement IDeref, IWatchable, IReset, ISwap, IMeta and IWithMeta."
+ [v]
+ (WrappedAtom. v))
+
+;; Or:
+;; Both wouldn't be implemented, but not sure right now which
+;; is better.
+
+;; TODO: Better name
+(defn reagent-deref
+ "Deref a Atom and register watcher to current Reactive
+ context, so that the context will be notified if the Atom
+ value is updated.
+
+ This will enable using Atom in place of RAtom and Reactions,
+ as long as you remember to use this function instead of directly
+ dereferecing the Atom."
+ [a]
+ (notify-deref-watcher! a)
+ @a)

test/reagenttest/testratom.cljs

@@ -483,3 +483,48 @@
  (pr-str (r/track (fn foo [] (:foo @x))))))
  (is (= "#object[reagent.ratom.Reaction {:val 1}]"
  (pr-str (reaction (:foo @x)))))))
+
+(deftest adapt-regular-atom-test
+ (testing "WrappedAtom"
+ (let [runs (running)
+ start (rv/->ratom (atom 0))
+ sv (reaction @start)
+ comp (reaction @sv (+ 2 @sv))
+ c2 (reaction (inc @comp))
+ count (rv/atom 0)
+ out (rv/atom 0)
+ res (reaction
+ (swap! count inc)
+ @sv @c2 @comp)
+ const (run!
+ (reset! out @res))]
+ (is (= @count 1) "constrain ran")
+ (is (= @out 2))
+ (reset! start 1)
+ (r/flush)
+ (is (= @out 3))
+ (is (<= 2 @count 3))
+ (dispose const)
+ (is (= (running) runs))))
+
+ (testing "reagent-deref"
+ (let [runs (running)
+ start (atom 0)
+ sv (reaction (rv/reagent-deref start))
+ comp (reaction @sv (+ 2 @sv))
+ c2 (reaction (inc @comp))
+ count (rv/atom 0)
+ out (rv/atom 0)
+ res (reaction
+ (swap! count inc)
+ @sv @c2 @comp)
+ const (run!
+ (reset! out @res))]
+ (is (= @count 1) "constrain ran")
+ (is (= @out 2))
+ (reset! start 1)
+ (r/flush)
+ (is (= @out 3))
+ (is (<= 2 @count 3))
+ (dispose const)
+ (is (= (running) runs)))))