Learn rspec

I don't know TDD or BDD or rspec. All I know is you need to test your code.

According to the odin project:
Rspec is a domain specific language written in Ruby to help you test your Ruby code. Oh man, you can't use it if you ever move to Javascript or something else. Not universal I suppose.

But I haven't yet been able to get my head around "why you have to write tests before you code". How does that even work? I don't even know what I'm going to code yet or how the code will be written and ... I have to test it? Well, I'm going to spend time to understand this (view  all my reading on the matter here). Meantime, below are some resources I find useful and confusing.

Helpful resources:

• the odin project
• betterspecs.org
• Rspec book

Confusing resources:

• Tuts Ruby for Newbies on Youtube - Blog post here. I wish the explanation for each "describe" was in plain English. It's not. You need some background of rspec before watching this video.
• Treehouse's An Introduction to Rspec - Assumes you have some rspec background.