old_contents: #!/usr/bin/env python
  # -*- coding: utf-8 -*-
  import pytest
  
  from flask import Flask, jsonify
  
  
  @pytest.fixture
  def app():
      app = Flask(__name__)
  
      @app.route('/ping')
      def ping():
          return jsonify(ping='pong')
  
      return app
  
new_contents: #!/usr/bin/env python
  # -*- coding: utf-8 -*-
  import pytest
  
  from flask import Flask, jsonify
  
  
  @pytest.fixture
  def app():
      app = Flask(__name__)
  
      @app.route('/')
      def index():
          return app.response_class('OK')
  
      @app.route('/ping')
      def ping():
          return jsonify(ping='pong')
  
      return app
  
subject: Add index route to test application