diff --git a/src/datomish/test_macros.cljc b/src/datomish/test_macros.cljc
index f88e3d6c..1f71e78c 100644
--- a/src/datomish/test_macros.cljc
+++ b/src/datomish/test_macros.cljc
@@ -3,6 +3,7 @@
 ;; file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 (ns datomish.test-macros
+  (:refer-clojure :exclude [with-open])
   (:require
    [datomish.pair-chan]))
 
@@ -35,3 +36,35 @@
        ~(with-meta name {:async true})
        (let [[v# e#] (clojure.core.async/<!! (datomish.pair-chan/go-pair ~@body))]
          (clojure.test/is (= e# nil))))))
+
+;; CLJS doesn't expose `with-open`, for reasons unknown.  Duplicate the definition of
+;; `with-open` (and `assert-args`) here.
+;; See https://github.com/clojure/clojure/blob/clojure-1.7.0/src/clj/clojure/core.clj#L3679-L3698.
+(defmacro ^{:private true} assert-args
+  [& pairs]
+  `(do (when-not ~(first pairs)
+         (throw (IllegalArgumentException.
+                  (str (first ~'&form) " requires " ~(second pairs) " in " ~'*ns* ":" (:line (meta ~'&form))))))
+       ~(let [more (nnext pairs)]
+          (when more
+            (list* `assert-args more)))))
+
+(defmacro with-open
+  "bindings => [name init ...]
+  Evaluates body in a try expression with names bound to the values
+  of the inits, and a finally clause that calls (.close name) on each
+  name in reverse order."
+  {:added "1.0"}
+  [bindings & body]
+  (assert-args
+    (vector? bindings) "a vector for its binding"
+    (even? (count bindings)) "an even number of forms in binding vector")
+  (cond
+    (= (count bindings) 0) `(do ~@body)
+    (symbol? (bindings 0)) `(let ~(subvec bindings 0 2)
+                              (try
+                                (with-open ~(subvec bindings 2) ~@body)
+                                (finally
+                                  (. ~(bindings 0) close))))
+    :else (throw (java.lang.IllegalArgumentException.
+                   "with-open only allows Symbols in bindings"))))