feat: allow multimethods as :handlers in validation

fixes #749

modules/reitit-core/src/reitit/spec.cljc

@@ -37,8 +37,11 @@
 ;; Default data
 ;;
 
+(defn -multi? [x]
+  (instance? #?(:clj clojure.lang.MultiFn :cljs cljs.core.MultiFn) x))
+
 (s/def ::name keyword?)
-(s/def ::handler (s/or :fn fn? :var var?))
+(s/def ::handler (s/or :fn fn? :var var? :multi -multi?))
 (s/def ::no-doc boolean?)
 (s/def ::conflicting boolean?)
 (s/def ::default-data

test/cljc/reitit/ring_spec_test.cljc

@@ -12,6 +12,9 @@
 (s/def ::role #{:admin :user})
 (s/def ::roles (s/and (s/coll-of ::role :into #{}) set?))
 
+(defmulti my-multi (constantly :default))
+(defmethod my-multi :default [x] x)
+
 (deftest route-data-validation-test
   (testing "validation is turned off by default"
     (is (r/router?
@@ -85,6 +88,12 @@
          (ring/router
           ["/api" {:handler identity
                    :middleware '()}]
+          {:validate rrs/validate}))))
+
+  (testing "handler can be a multimethod"
+    (is (r/router?
+         (ring/router
+          ["/api" {:get {:handler my-multi}}]
           {:validate rrs/validate})))))
 
 (deftest coercion-spec-test