1 files changed, 16 insertions, 0 deletions
diff --git a/util/deferred_test.ts b/util/deferred_test.ts
new file mode 100644
index 000000000..a397b3012
--- /dev/null
+++ b/util/deferred_test.ts
@@ -0,0 +1,16 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { assert, test } from "../testing/mod.ts";
+import { defer, isDeferred } from "./deferred.ts";
+
+test(async function asyncIsDeferred() {
+  const d = defer();
+  assert.assert(isDeferred(d));
+  assert.assert(
+    isDeferred({
+      promise: null,
+      resolve: () => {},
+      reject: () => {}
+    }) === false
+  );
+});