unit testing

The SendGrid mailer API is pretty basic. Let's first focus on unit testing those basic functions. One approach to testing a "unit under test" is to break out the input and outputs of the unit itself and any dependencies it has. A well-designed function (or a very simple one like this) should have clear inputs outputs and dependencies.

For any module we should ask:

• What does our function under test do?

• What are the possible inputs to the function, and it's dependencies?

• What are the possible outputs?