add: unit and integration testing

app/node_modules/escape-string-regexp/index.js

@@ -0,0 +1,11 @@
+'use strict';
+
+const matchOperatorsRegex = /[|\\{}()[\]^$+*?.-]/g;
+
+module.exports = string => {
+	if (typeof string !== 'string') {
+		throw new TypeError('Expected a string');
+	}
+
+	return string.replace(matchOperatorsRegex, '\\$&');
+};