How to test via rspec that session variables updated in controller

How to test via rspec that session variables updated in controller

I am trying to write a test using rspec that tests if the the session
variable was correctly changed:
This is the part of the GamesController I want to test:
def change_player
if session[:player] == 0
session[:player] = 1
else
session[:player] = 0
end
end
This is my game_spec.rb file:
require "spec_helper"
describe GamesController do
describe "#change_player" do
it "should change player to 1" do
session[:player] = 0
get :change_player
assigns(session[:player]).should == 1
end
end
end
This is the error message I get when I run the test:
Failures:
1) GamesController#change_player should set player to 0
Failure/Error: session[:player] = 0
NameError:
undefined local variable or method `session' for
#<RSpec::Core::ExampleGroup::Nested_1::Nested_1:0x00000103b3b0d8>
# ./spec/features/game_spec.rb:6:in `block (3 levels) in <top
(required)>'
Finished in 0.01709 seconds
1 example, 1 failure
Failed examples:
rspec ./spec/features/game_spec.rb:5 # GamesController#change_player
should set player to 0
Thanks