add module exports to unittest.js

Signed-off-by: Arthur Lu <learthurgo@gmail.com>

unittest/unittest.js

@@ -4,4 +4,6 @@ function test(name, items) {}
 
 function item(name, method) {}
 
-function assert(result, expected) {}
+function assert(result, expected) {}
+
+module.exports = {environment, test, item, assert};