Some confusion on ARGV.

If I have a file, say, Test.rb, with the line:

   p ARGV

And, say, it exists in a directory with some
other ruby files, a.rb, b.rb, and c.rb.

Then I invoke it like:

   ruby Test.rb -> []
   ruby Test.rb *.py -> ["*.py"]
   ruby Test.rb *.rb -> ["Test.rb", "a.rb", "b.rb", "c.rb"]

The first two cases I expected, but for the third
I expected ["*.rb"] rather than the expanded
wildcard output.

Is this behavior correct? Is it documented somewhere?
Is there documentation on any other anomalies with
ARGV?