Inegration context for RSpec

ActionDispatch::Testing::Integration requires smth else and
defines Rails, so had to change `defined?(Rails)` all over the code.

spec/telegram/bot/rspec/integration_spec.rb

@@ -0,0 +1,62 @@
+require 'telegram/bot/rspec/integration'
+require 'action_controller'
+require 'action_dispatch'
+require 'action_dispatch/testing/integration'
+
+RSpec.describe 'Integrations helper', :telegram_bot do
+  include ActionDispatch::Integration::Runner
+
+  let(:app) { Telegram::Bot::Middleware.new(bot, controller) }
+  let(:bot) { Telegram::Bot::ClientStub.new('token') }
+  let(:controller_path) { '/' }
+  let(:controller) do
+    Class.new(Telegram::Bot::UpdatesController) do
+      def start(*args)
+        respond_with :message, text: "Start: #{args.inspect}, option: #{payload[:option]}"
+      end
+    end
+  end
+
+  describe '#default_message_options' do
+    subject { default_message_options }
+    it { should eq from: {id: from_id}, chat: {id: chat_id} }
+  end
+
+  describe '#dispatch' do
+    subject { -> { dispatch message: {text: '/start', **default_message_options} } }
+    it { should respond_with_message 'Start: [], option: ' }
+  end
+
+  describe '#dispatch_message' do
+    subject { -> { dispatch_message "/start #{args.join ' '}", options } }
+    let(:args) { %w(asd qwe) }
+    let(:options) { {} }
+    it { should respond_with_message "Start: #{args.inspect}, option: " }
+
+    context 'with options' do
+      let(:options) { {option: 1} }
+      it { should respond_with_message "Start: #{args.inspect}, option: 1" }
+
+      context 'and chat_id is not set' do
+        let(:options) { super().merge(chat: nil) }
+        it { should raise_error(/chat is not present/) }
+      end
+    end
+  end
+
+  describe '#dispatch_command' do
+    subject { -> { dispatch_command :start, *args } }
+    let(:args) { [] }
+    it { should respond_with_message "Start: #{args.inspect}, option: " }
+
+    context 'with args' do
+      let(:args) { %w(asd qwe) }
+      it { should respond_with_message "Start: #{args.inspect}, option: " }
+    end
+
+    context 'with options' do
+      let(:args) { ['asd', 'qwe', option: 1] }
+      it { should respond_with_message "Start: #{args[0...-1].inspect}, option: 1" }
+    end
+  end
+end