Unit testing the app.config file with NUnit

Question

When you guys are unit testing an application that relies on values from an app.config file? How do you test that those values are read in correctly and how your program re

Answer 1

A more elegant solution is to use plain old dependency injection on the configuration settings themselves. IMHO this is cleaner than having to mock a configuration reading class/wrapper etc.

For example, say a class "Weather" requires a "ServiceUrl" in order to function (e.g. say it calls a web service to get the weather). Rather than having some line of code that actively goes to a configuration file to get that setting (whether that code be in the Weather class or a separate configuration reader that could be mocked as per some of the other responses), the Weather class can allow the setting to be injected, either via a parameter to the constructor, or possibly via a property setter. That way, the unit tests are extremely simple and direct, and don't even require mocking.

The value of the setting can then be injected using an Inversion of Control (or Dependency Injection) container, so the consumers of the Weather class don't need to explicitly supply the value from somewhere, as it's handled by the container.