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

node_modules/lodash/isInteger.js

@@ -0,0 +1,33 @@
+var toInteger = require('./toInteger');
+
+/**
+ * Checks if `value` is an integer.
+ *
+ * **Note:** This method is based on
+ * [`Number.isInteger`](https://mdn.io/Number/isInteger).
+ *
+ * @static
+ * @memberOf _
+ * @since 4.0.0
+ * @category Lang
+ * @param {*} value The value to check.
+ * @returns {boolean} Returns `true` if `value` is an integer, else `false`.
+ * @example
+ *
+ * _.isInteger(3);
+ * // => true
+ *
+ * _.isInteger(Number.MIN_VALUE);
+ * // => false
+ *
+ * _.isInteger(Infinity);
+ * // => false
+ *
+ * _.isInteger('3');
+ * // => false
+ */
+function isInteger(value) {
+  return typeof value == 'number' && value == toInteger(value);
+}
+
+module.exports = isInteger;