gistfile1.rb

describe Foo
  describe ".setup" do
    it "should capture a Mongo connection for the specified environment host" do
      Mongo::Connection.stub(:new) { |param| param.should == host }
      Foo.setup config, environment
    end
  end

  describe ".connection" do

    it "should assign to the Mongo connection the host for the specified environment" do
      Foo.setup(config, environment).connection.host.should == host
    end
  end
end

describe Foo
  let ...
  describe ".setup" do
    it "should init a new Mongo connection for the specified environment host" do
       Mongo::Connection.should_receive(:new).with(host)
       Foo.setup config, :test
    end
  end

  describe ".connection" do
    it "should return the created Mongo connection on setup" do
      Mongo::Connection.stub(:new).and_return(connection)
      Foo.setup config, :test
      Foot.connection.should == connection
    end
  end
end