added unit testing, and started implementing unit tests...phew

node_modules/lodash/_arrayPush.js

@@ -0,0 +1,20 @@
+/**
+ * Appends the elements of `values` to `array`.
+ *
+ * @private
+ * @param {Array} array The array to modify.
+ * @param {Array} values The values to append.
+ * @returns {Array} Returns `array`.
+ */
+function arrayPush(array, values) {
+  var index = -1,
+      length = values.length,
+      offset = array.length;
+
+  while (++index < length) {
+    array[offset + index] = values[index];
+  }
+  return array;
+}
+
+module.exports = arrayPush;