Projects::BoardsController#show returns a list of board lists

app/controllers/projects/boards_controller.rb

 class Projects::BoardsController < Projects::ApplicationController
   def show
-    Boards::CreateService.new(project).execute
+    board = Boards::CreateService.new(project).execute
 
     respond_to do |format|
       format.html
+      format.json { render json: board.lists.as_json(only: [:id, :list_type, :position], methods: [:title], include: { label: { only: [:id, :title, :color] } }) }
     end
   end
 end

spec/controllers/projects/boards_controller_spec.rb

@@ -10,10 +10,13 @@ describe Projects::BoardsController do
   end
 
   describe 'GET #show' do
-    it 'creates a new board when project does not have one' do
+    context 'when project does not have a board' do
+      it 'creates a new board' do
         expect { get :show, namespace_id: project.namespace.to_param, project_id: project.to_param }.to change(Board, :count).by(1)
       end
+    end
 
+    context 'when format is HTML' do
       it 'renders HTML template' do
         get :show, namespace_id: project.namespace.to_param, project_id: project.to_param
 
@@ -21,4 +24,28 @@ describe Projects::BoardsController do
         expect(response.content_type).to eq 'text/html'
       end
     end
+
+    context 'when format is JSON' do
+      it 'returns a successful 200 response' do
+        get :show, namespace_id: project.namespace.to_param, project_id: project.to_param, format: :json
+
+        expect(response).to have_http_status(200)
+        expect(response.content_type).to eq 'application/json'
+      end
+
+      it 'returns a list of board lists' do
+        board = project.create_board
+        create(:backlog_list, board: board)
+        create(:list, board: board)
+        create(:done_list, board: board)
+
+        get :show, namespace_id: project.namespace.to_param, project_id: project.to_param, format: :json
+
+        parsed_response = JSON.parse(response.body)
+
+        expect(response).to match_response_schema('list', array: true)
+        expect(parsed_response.length).to eq 3
+      end
+    end
+  end
 end

spec/fixtures/api/schemas/list.json

+{
+  "type": "object",
+  "required" : [
+    "id",
+    "list_type",
+    "title",
+    "position"
+  ],
+  "properties" : {
+    "id": { "type": "integer" },
+    "list_type": {
+      "type": "string",
+      "enum": ["backlog", "label", "done"]
+    },
+    "label": {
+      "type": ["object"],
+      "required": [
+        "id",
+        "color",
+        "title"
+      ],
+      "properties": {
+        "id": { "type": "integer" },
+        "color": {
+          "type": "string",
+          "pattern": "^#[0-9A-Fa-f]{3}{1,2}+$"
+        },
+        "title": { "type": "string" }
+      }
+    },
+    "title": { "type": "string" },
+    "position": { "type": ["integer", "null"] }
+  },
+  "additionalProperties": false
+}

spec/support/api/schema_matcher.rb

+RSpec::Matchers.define :match_response_schema do |schema, options = {}|
+  match do |response|
+    schema_directory = "#{Dir.pwd}/spec/fixtures/api/schemas"
+    schema_path = "#{schema_directory}/#{schema}.json"
+    list = options.fetch(:array, false)
+
+    JSON::Validator.validate!(schema_path, response.body, list: list)
+  end
+end