Choosing what to test
Testing is the process we apply in order to make sure that software applications work as expected.
Sounds easy, but it is not.
Starting from the outside in approach, the first form of validation is writing an acceptance criteria for a feature that may include many valid scenarios. This kind of test is called aceptance testing, should be end to end crossing all the layers and, a black box in the sense we don’t know the details of how it is implemented.