Test different ways to declare fn should be used as functional component

src/reagent/impl/template.cljs

@@ -155,14 +155,6 @@
  ;; https://www.w3.org/TR/custom-elements/#custom-elements-core-concepts
  (not= -1 (.indexOf tag "-")))))
 
-(defn reag-element [tag v compiler]
- (let [c (comp/as-class tag compiler)
- jsprops #js {}]
- (set! (.-argv jsprops) v)
- (when-some [key (util/react-key-from-vec v)]
- (set! (.-key jsprops) key))
- (react/createElement c jsprops)))
-
 (defn function-element [tag v first-arg compiler]
  (let [jsprops #js {}]
  (set! (.-reagentRender jsprops) tag)
@@ -172,6 +164,17 @@
  (set! (.-key jsprops) key))
  (react/createElement (comp/functional-render-fn compiler tag) jsprops)))
 
+(defn reag-element [^clj tag v compiler]
+ (if (or (:functional (meta tag))
+ (.-functional tag))
+ (function-element tag v 1 compiler)
+ (let [c (comp/as-class tag compiler)
+ jsprops #js {}]
+ (set! (.-argv jsprops) v)
+ (when-some [key (util/react-key-from-vec v)]
+ (set! (.-key jsprops) key))
+ (react/createElement c jsprops))))
+
 (defn maybe-function-element
  "If given tag is a Class, use it as a class,
  else wrap in Reagent function wrapper."

test/reagenttest/testreagent.cljs

@@ -1604,16 +1604,58 @@
  (r/flush)
  (is (= 3 @render))))))))
 
+(defn ^:functional f1
+ [x]
+ [:span "Hello " x])
+
+(defn f2
+ {:functional true}
+ [x]
+ [:span "Hello " x])
+
+(defn f3
+ [x]
+ [:span "Hello " x])
+(set! (.-functional ^clj f3) true)
+
+; (js/console.log f1 (pr-str (meta f1)) (pr-str (meta #'f1)))
+; (js/console.log f2 (pr-str (meta f2)) (pr-str (meta #'f2)))
+
 (deftest functional-component-poc-simple
  (when r/is-client
  (let [c (fn [x]
- [:span "Hello " x])]
+ [:span "Hello " x])
+ f0 (with-meta c {:functional true})]
  (testing ":f>"
  (with-mounted-component [:f> c "foo"]
  (fn [c div]
  (is (nil? c) "Render returns nil for stateless components")
  (is (= "Hello foo" (.-innerText div))))))
 
+ (testing "with-meta"
+ (with-mounted-component [f0 "foo"]
+ (fn [c div]
+ (is (nil? c) "Render returns nil for stateless components")
+ (is (= "Hello foo" (.-innerText div))))))
+
+ (testing "defn symbol meta"
+ (with-mounted-component [#'f1 "foo"]
+ (fn [c div]
+ (is (nil? c) "Render returns nil for stateless components")
+ (is (= "Hello foo" (.-innerText div))))))
+
+ (testing "defn fn meta"
+ (with-mounted-component [#'f2 "foo"]
+ (fn [c div]
+ (is (nil? c) "Render returns nil for stateless components")
+ (is (= "Hello foo" (.-innerText div))))))
+
+ (testing "fn property"
+ (with-mounted-component [f3 "foo"]
+ (fn [c div]
+ (is (nil? c) "Render returns nil for stateless components")
+ (is (= "Hello foo" (.-innerText div))))))
+
  (testing "compiler options"
  (with-mounted-component [c "foo"]
  functional-compiler