How to get the name of a double.

named_doubles.rb

# to get the name, you can use `instance_variable_get`:
tweet = double("Twitter::Tweet")
tweet.instance_variable_get(:@name) # => "Twitter::Tweet"

# that's clearly violating the public API, though. Another way is to pass it as a stub:
tweet = double("Twitter::Tweet", name: "Twitter::Tweet")
tweet.name # => "Twitter::Tweet"

# If you like that approach, you could create a new `named_double`
# helper method:
module NamedDoubles
  def named_double(name, stubs={})
    double(name, stubs.merge(name: name))
  end
end

RSpec.configure do |config|
  config.include NameableDoubles
end

tweet = named_double("Twitter::Tweet")
tweet.name # => "Twitter::Tweet"