add items controller with spec

app/controllers/items_controller.rb

@@ -1,2 +1,41 @@
 class ItemsController < ApplicationController
+   before_action :set_todo
+   before_action :set_todo_item, only: [:show, :update, :destroy]
+
+   # GET /todos/:todo_id/items 
+   def index
+       json_response(@todo.items) 
+   end
+
+    # GET /todos/:todo_id/items/:id
+    def show
+        json_response(@item) 
+    end 
+
+    # POST /todos/:todo_id/items
+    def create
+        @todo.items.create!(item_params)
+        json_response(@todo, :created) 
+    end
+
+    # PUT /todos/:todo_id/items/:id
+    def destroy
+        @item.destroy
+        head :no_content
+    end 
+
+
+    private 
+
+    def item_params
+        params.permit(:name, :done) 
+    end 
+
+    def set_todo
+      @todo = Todo.find(params[:id]) 
+    end 
+
+    def set_todo_item
+        @item = @todo.items.find_by!(id:  params[:id]) if @todo 
+    end 
 end

spec/requests/items_spec.rb

@@ -1,7 +1,68 @@
 require 'rails_helper'
 
-RSpec.describe "Items", type: :request do
-  describe "GET /index" do
-    pending "add some examples (or delete) #{__FILE__}"
+RSpec.describe "Items API" do
+  #Initialize the test data
+  let!(:todo) { create(:todo) }
+  let!(:items) { create_list(:item, 20, todo_id: todo.id) }
+  let(:todo_id) { todo.id }
+  let(:id) { items.first.id }
+
+  # Test suite for GET /todos/:todo_id/items
+  describe "GET /todos/:todo_id/items" do
+    before { get "/todo/#{todo_id}/items" }
+
+    context 'when todo exists' do 
+      it 'returns status code 200' do
+        expect(response).to have_http_status(200)
+      end
+
+      it 'returns all todo items' do 
+        expect(json.size).to eq(20)
+      end 
+    end 
+    context 'when todo does not exist' do 
+      let(:todo_id) { 0 }
+
+      it 'returns status code 404' do
+        expect(response).to have_http_status(404) 
+      end 
+
+      it 'returns a not found message' do 
+        expect(response.body).to match(/Couldn't find Todo/)
+      end 
+    end 
+  end 
+
+    # Test suite for PUT /todos/:todo_id/items
+    describe 'POST /todos/:todo_id/items' do 
+      let(:valid_attributes) { { name: "visit narnia", done: false } }
+
+      context "when request attributes are valid" do 
+        before { post "/todos/#{todo_id}/items", params: valid_attributes }
+
+        it "returns status code 201" do
+          expect(response).to have_http_status(201) 
+        end  
+      end
+
+      context "when an invalid request" do
+        before { post "/todos/{todo_id}/items", params: {} }
+
+        it "returns status code 422" do
+          expect(response).to  have_http_status(422)
+        end 
+
+        it "returns a failure message" do 
+          expect(response.body).to match(/Validation failed: Name can't be blank/)
+        end 
+      end 
+    end 
+    # Test suite for DELETE /todos/:id
+    describe 'DELETE /todos/:id' do 
+      before { delete "/todos/#{todo_id}/items/#{id}"}
+
+      it "returns status code 204" do 
+        expect(response).to have_http_status(204)
+      end 
+    end  
   end
-end