Unit testing http requests to rest api

Question

I have a C# library that gets data from public api. trying to get into TDD and was wondering how to unit test a library that the main focus of it is to get data from the server and convert the json to .net objects. (Basically handling the http requests along with limiting and error handling and some configuration settings)
I know you should mock some sort of database but not sure how exactly. And i've read that the tests should run all the time even with internet connection off.

Answer 1

You can implement only integration testing. You also can test your code with internet connection off - just create a kind of wrapper. Among various design patterns the most appropriate is Facade for this kind of task. Create Facade around third-party library so you can mock this facade in future and make it produce desired/undesired results so you can unit test your classes. But: Don't test or mock what you don't own