add: unit and integration testing

app/node_modules/string-length/index.js

@@ -0,0 +1,19 @@
+'use strict';
+const stripAnsi = require('strip-ansi');
+const charRegex = require('char-regex');
+
+const stringLength = string => {
+	if (string === '') {
+		return 0;
+	}
+
+	const strippedString = stripAnsi(string);
+
+	if (strippedString === '') {
+		return 0;
+	}
+
+	return strippedString.match(charRegex()).length;
+};
+
+module.exports = stringLength;