Nashorn smaller fail case

failure

The minimal error (below) disappears when test-919-generic-cas is deleted. It seems to be that the Protocol clashing comes when MyCustomAtom is used, not only defined. The error also disappears if `state` inside MyCustomAtom is changed to snail. Note that Volatile in cljs.core is also defined in terms of a state attribute.

Note that even though `compare-and-set!` calls `-deref` it raises no exceptions.

ERROR in (test-919-generic-cas) (Error:NaN:NaN)
testing CLJS-919, CAS should on custom atom types
expected: (== (clojure.core/deref a0) 20)
  actual: 
#<Error: No protocol method IDeref.-deref defined for type cljs.core-test/MyCustomAtom: [object Object]>

Ran 2 tests containing 2 assertions.
0 failures, 1 errors.
Tested with 1 out of 4 possible js targets

tesfile.clj

(ns cljs.core-test
  (:refer-clojure :exclude [iter])
  (:require [cljs.test :refer-macros [deftest testing is]]))

(deftest test-atoms-and-volatile
  (let [v (volatile! 1)]
    (testing "Testing volatile"
      (is (= 1 (-deref v))))))

(deftype MyCustomAtom [state]
  IDeref
  (-deref [_] state))

(deftest test-919-generic-cas
  (testing "testing CLJS-919, CAS should on custom atom types"
    (let [a0 (MyCustomAtom. 10)]
      (is (== (-deref a0) 10)))))