codys_test.rb

describe(List) do
  describe("#tasks") do
    it("tells which tasks are in it") do
      test_list = List.create({:name => "list"})
      test_task1 = Task.create({:description => "task1", :list_id => test_list.id})
      test_task2 = Task.create({:description => "task2", :list_id => test_list.id})
     expect(test_list.tasks()).to(eq([test_task1, test_task2]))
    end
  end
end

my_test.rb

describe(List) do
  describe "A list with tasks" do
    it "has a list of tasks" do
      list     = List.create({:name => "Times I Farted"}).id
      task_one = Task.create({description: "morning",   :list_id => list.id })
      task_two = Task.create({description: "breakfast", :list_id => list.id })
      tasks    = list.tasks
      expect(tasks.include? task_one).to eq true
      expect(tasks.include? task_two).to eq true
    end
  end
end