Are there fictional test users for LinkedIn or Facebook?

Question

Do either LinkedIn or Facebook provide a fictional user ID that can be used for testing an app that calls their APIs?

Answer 1

Facebook provides test users for app developers:

Test Users for Apps

A test user is a special Facebook account, invisible to real accounts, which can be created within an app for the purpose of manual or automated testing of that app's Facebook integration.

We ensure that test users are exempt from our spam and fake account detection systems so that you can test your app without worrying about getting disabled.

You can create, access and delete test user accounts in a couple of ways - by using the Graph API to do it programmatically, or by using the App Dashboard to do it manually.

As for LinkedIn, this SO question may be useful: A full LinkedIn profile for testing an app