This presentation is part of the Declarative Expressions Self-Study Course.
As always, you can create and unit test activities to test your declarative expressions. To help in this unit testing, create a parameter that will allow you to easily change the values of properties and see how the results are changed.
You can also use the Run icon on the Expressions Rule to display the Run Rule window, which has all the testing features built in. You can see the declarative network and click on each input property to set its value and see what happens in each scenario.
The test team on your projects should know about this very useful feature and how to use it.