How to Test an App?

Testing approach

One of the most difficult aspects of testing for beginners is knowing how to test. More specifically, knowing what should and shouldn’t be tested. We’ll illustrate this with an example.

Imagine we had an alien companion named Adder who follows us everywhere we go. Adder can only do one thing, add two numbers together.

To verify Adder’s ability to add two numbers, we could generate a set of test cases to see if Adder provides us with the correct answer. So, we could provide Adder with two positive numbers (2, 4), a positive number and a zero (3, 0), a positive number and a negative number (5, -2), and so on.

When we test Adder, we aren’t necessarily concerned with how Adder arrives at the answer. We only care about the answer Adder provides us. In other words, we only care that Adder behaves as expected, we don’t care about Adder’s implementation.