Adding 3A testing practice

[dvinciguerra]

Hi, again! :)

I opened this issue to talk about the possibility to add 3A or AAA (Arrange, Act and Asset) as testing good practice.

The 3A describes that a good practice when we are writing tests is keep the 3 simple steps to make it more simple and easy to read.

Example:

# arrange
some_text = "Hello from webpro/programming-principles"

# act
reversed_text = revese_string(some_text)

# assert
reversed_text == "selpicnirp-gnimmargorp/orpbew morf olleH"

A reference: https://xp123.com/articles/3a-arrange-act-assert/

Congrats by this awesome repo! :)
Thanks

[webpro]

Somehow the issues weren't automatically closed. Anyway, thanks @dvinciguerra, your suggestions have been added.

[dvinciguerra]

Thanks @webpro
Count with me to help!

Best,