method_forwarding_demo.rb

# NB: this example uses a test-framework called m-spec
# https://github.com/dearshrewdwit/m-spec
# Follow along with the screen recording here: https://youtu.be/c5dg-LPQp2E

# ---------------------------------------------------------------------------

# ./lib/todo_list.rb

require_relative "todo.rb"

class TodoList
  def initialize
    @todos = []
  end

  def add(description, todo_class = Todo)
    @todos << todo_class.new(description)
  end

  def get(index)
    all[index]
  end

  def set_complete(index)
    get(index).complete
  end

  def to_string
    all.map.with_index do |todo, index|
      "#{index + 1}. #{todo.to_string}"
    end.join("\n")
  end

  private

  def all
    @todos
  end
end

# ---------------------------------------------------------------------------

# ./lib/todo.rb

class Todo
  STATUSES = {
    true => 'complete',
    false => 'not complete'
  }
  attr_reader :description, :status

  def initialize(description)
    @description = description
    @status = false
  end

  def complete
    @status = true
  end

  def to_string
    "#{description} #{STATUSES[status]}"
  end
end

# ---------------------------------------------------------------------------

# ./spec/feature_spec.rb

require "./lib/todo_list.rb"

describe "TodoList features" do
  it "can create a todo" do
    list = TodoList.new
    list.add("say hi")
    expect(list.to_string).to eq("1. say hi not complete")
  end

  it "can complete a todo" do
    list = TodoList.new
    list.add("say hi")
    list.set_complete(0)
    expect(list.to_string).to eq("1. say hi complete")
  end

  it "can print some todos" do
    list = TodoList.new
    list.add("say hi")
    list.add("say howdy")
    expect(list.to_string)
      .to eq("1. say hi not complete\n2. say howdy not complete")
  end
end

# ---------------------------------------------------------------------------

# ./spec/todo_list_spec.rb

require "./lib/todo_list.rb"

describe TodoList do
  describe "creation" do
    it "creates a list with no todos" do
      todo_list = TodoList.new
      expect(todo_list.get(0)).to eq nil
    end
  end

  describe "adding a todo" do
    it "stores a todo with a description" do
      todo = test_double('a todo')
      todo_class = test_double('todo_class')
      allow(todo_class).to receive(:new) { todo }
      todo_list = TodoList.new
      result = todo_list.add("say hi", todo_class)

      expect(result).to eq [todo]
    end
  end

  describe "getting a todo" do
    it "gets a todo at an index" do
      todo = test_double('a todo')
      todo_class = test_double('todo_class')
      allow(todo_class).to receive(:new) { todo }
      todo_list = TodoList.new
      todo_list.add("say hi", todo_class)

      expect(todo_list.get(0)).to eq todo
    end
  end

  describe 'a list of todos' do
    it 'a string of todos with index' do
      todo = test_double('a todo')
      allow(todo).to receive(:to_string) { 'say hi not complete' }
      todo_class = test_double('todo_class')
      allow(todo_class).to receive(:new) { todo }
      todo_list = TodoList.new
      todo_list.add("say hi", todo_class)

      expect(todo_list.to_string).to eq "1. say hi not complete"
    end

    it 'lots of strings of todos with index' do
      todo = test_double('a todo')
      allow(todo).to receive(:to_string) { 'say hi not complete' }
      todo_class = test_double('todo_class')
      allow(todo_class).to receive(:new) { todo }
      todo_list = TodoList.new
      todo_list.add("say hi", todo_class)
      todo_list.add("say hi", todo_class)

      expect(todo_list.to_string).to eq "1. say hi not complete\n2. say hi not complete"
    end
  end

  describe '#set_complete' do
    it 'asks a todo to be complete' do
      todo = test_double('a todo')
      allow(todo).to receive(:complete) { true }
      todo_class = test_double('todo_class')
      allow(todo_class).to receive(:new) { todo }
      todo_list = TodoList.new
      todo_list.add("say hi", todo_class)

      expect(todo_list.set_complete(0)).to eq true
    end
  end
end

# ---------------------------------------------------------------------------

# ./spec/todo_spec.rb

require "./lib/todo.rb"

describe 'Todo' do
  describe "creation" do
    it "creates a todo" do
      todo = Todo.new("say hi")
      expect(todo.class).to eq Todo
    end
  end

  describe '#description' do
    it 'returns description' do
      todo = Todo.new("say hi")

      expect(todo.description).to eq "say hi"
    end
  end

  describe '#state' do
    it 'returns status' do
      todo = Todo.new("say hi")

      expect(todo.status).to eq false
    end
  end

  describe '#complete' do
    it 'sets status to true' do
      todo = Todo.new("say hi")
      todo.complete
      expect(todo.status).to eq true
    end
  end

  describe '#to_string' do
    it 'returns string when not complete' do
      todo = Todo.new("say hi")

      expect(todo.to_string).to eq "say hi not complete"
    end

    it 'returns string when complete' do
      todo = Todo.new("say hi")
      todo.complete

      expect(todo.to_string).to eq "say hi complete"
    end
  end
end