Like I mentioned yesterday, there's no technical limitations for what goes in the quotes in a describe block, but there are some conventions to be aware of.

When you're testing the name of a method on an object, it's typical to do something like "describe #method_name".  The hash in front of the name indicates that it's an actual method on the object you're testing.

What you're testing in this example is actually the initialize method, so I'd alter your describe block to say "describe #initialize"