Add UserData ioDevice for setting and getting username from blocks

test/unit/io_userData.js

@@ -0,0 +1,25 @@
+const test = require('tap').test;
+const UserData = require('../../src/io/userData');
+
+test('spec', t => {
+    const userData = new UserData();
+
+    t.type(userData, 'object');
+    t.type(userData.postData, 'function');
+    t.type(userData.getUsername, 'function');
+    t.end();
+});
+
+test('getUsername returns empty string initially', t => {
+    const userData = new UserData();
+
+    t.strictEquals(userData.getUsername(), '');
+    t.end();
+});
+
+test('postData sets the username', t => {
+    const userData = new UserData();
+    userData.postData({username: 'TEST'});
+    t.strictEquals(userData.getUsername(), 'TEST');
+    t.end();
+});