Add endpoint to allow users to create a new board list

app/controllers/projects/board_lists_controller.rb

+class Projects::BoardListsController < Projects::ApplicationController
+  def create
+    list = Boards::Lists::CreateService.new(project, list_params).execute
+
+    respond_to do |format|
+      if list.valid?
+        format.json { render json: list.as_json(only: [:id, :list_type, :position], methods: [:title], include: { label: { only: [:id, :title, :color] } }) }
+      else
+        format.json { render json: list.errors, status: :unprocessable_entity }
+      end
+    end
+  end
+
+  private
+
+  def list_params
+    params.require(:list).permit(:label_id)
+  end
+end

config/routes.rb

@@ -856,7 +856,9 @@ Rails.application.routes.draw do
           end
         end
 
-        resource :board, only: [:show]
+        resource :board, only: [:show] do
+          resources :lists, only: [:create], controller: :board_lists
+        end
 
         resources :todos, only: [:create]
 

spec/controllers/projects/board_lists_controller_spec.rb

+require 'spec_helper'
+
+describe Projects::BoardListsController do
+  let(:project) { create(:project_with_board) }
+  let(:user)    { create(:user) }
+
+  before do
+    project.team << [user, :master]
+    sign_in(user)
+  end
+
+  describe 'POST #create' do
+    context 'with valid params' do
+      let(:label) { create(:label, project: project, name: 'Development') }
+
+      it 'returns a successful 200 response' do
+        post :create, namespace_id: project.namespace.to_param,
+                      project_id: project.to_param,
+                      list: { label_id: label.id },
+                      format: :json
+
+        expect(response).to have_http_status(200)
+      end
+
+      it 'returns the created list' do
+        post :create, namespace_id: project.namespace.to_param,
+                      project_id: project.to_param,
+                      list: { label_id: label.id },
+                      format: :json
+
+        expect(response).to match_response_schema('list')
+      end
+    end
+
+    context 'with invalid params' do
+      it 'returns an error' do
+        post :create, namespace_id: project.namespace.to_param,
+                      project_id: project.to_param,
+                      list: { label_id: nil },
+                      format: :json
+
+        parsed_response = JSON.parse(response.body)
+
+        expect(parsed_response['label']).to contain_exactly "can't be blank"
+        expect(response).to have_http_status(422)
+      end
+    end
+  end
+end