When writing Unit Tests, you will need to create test data objects for sure. Usually, those objects have tiny differences between different test cases.
There's a pattern that I especially like when I'm doing this is C#. The Builder Pattern.
Let's see how it would look like using the builder pattern in JS:
As you can see, there's a lot of code needed to implement it.
How can we do it more simply?
The basic idea is to use the Spread Operator to customize a default object.
Let's see how: