Here's how you can check the contents of the EntityValidationErrors in Visual Studio (without writing any extra code) i.e. during Debugging in the IDE.
The Problem?
You are right, the Visual Studio debugger's View Details Popup doesn't show the actual errors inside the EntityValidationErrors collection .
The Solution!
Just add the following expression in a Quick Watch window and click Reevaluate.
((System.Data.Entity.Validation.DbEntityValidationException)$exception).EntityValidationErrors
In my case, see how I am able to expand into the ValidationErrors List inside the EntityValidationErrors collection
References: mattrandle.me blog post, @yoel's answer
