rspec users - Nov 2010 - for web apps, when to use webrat, when to spec controllers?

Hi,

I''m trying to better understand when to use the integration testing
approach a la, say, Webrat, and when to rely on spec''ing my (Rails)
controllers (MVC pattern). Let me give the current example that has
brought me to indecision over which to use.

Attributes of a child object depend on changes in the parent. When the
child is thus changed, the web app user is to be informed with a
message in the edit view for the child. There are several messages
that can be displayed together or separately, depending on the
circumstances.

What''s the deal here? Does the fact that this involves another model
-- the parent -- mean this is an integration test?

Lille