Don't use Rails.cache as fallback for session_store

It's NullStore in development by default so session does not work,
and indeed should not be dependent.

lib/telegram/bot/railtie.rb

@@ -18,7 +18,7 @@ module Telegram
 
         ActiveSupport.on_load('telegram.bot.updates_controller') do
           self.logger = options.logger || Rails.logger
-          self.session_store = options.session_store || Rails.cache
+          self.session_store = options.session_store if options.session_store
         end
       end
 

spec/integration/requests/default_bot_spec.rb

@@ -5,4 +5,9 @@ RSpec.describe DefaultBotController, :telegram_bot, type: :request do
     subject { -> { dispatch_command :start } }
     it { should respond_with_message 'from default' }
   end
+
+  describe '#load_session' do
+    subject { -> { dispatch_command :load_session } }
+    it { should_not raise_error }
+  end
 end

spec/integration/requests/other_bot_spec.rb

@@ -6,4 +6,9 @@ RSpec.describe OtherBotController, :telegram_bot, type: :request do
     subject { -> { dispatch_command :start } }
     it { should respond_with_message 'from other' }
   end
+
+  describe '#load_session' do
+    subject { -> { dispatch_command :load_session } }
+    it { should raise_error(/session_store is not configured/) }
+  end
 end

spec/integration_helper.rb

@@ -4,6 +4,7 @@ require 'action_dispatch'
 require 'action_dispatch/testing/integration'
 
 require 'rails'
+require 'telegram/bot/railtie'
 require 'rspec/rails/adapters'
 require 'rspec/rails/fixture_support'
 require 'rspec/rails/example/rails_example_group'
@@ -13,6 +14,7 @@ ENV['RAILS_ENV'] = 'test'
 class TestApplication < Rails::Application
   config.eager_load = false
   config.log_level = :debug
+  config.action_dispatch.show_exceptions = false
   secrets[:secret_key_base] = 'test'
   secrets[:telegram] = {
     bot: 'default_token',
@@ -34,6 +36,18 @@ Rails.application.initialize!
   Object.const_set("#{bot_name}_bot_controller".camelize, controller)
 end
 
+[DefaultBotController, OtherBotController].each do |klass|
+  klass.class_eval do
+    use_session!
+
+    define_method :load_session do |*|
+      session[:test]
+    end
+  end
+end
+
+DefaultBotController.session_store = :memory_store
+
 RSpec.configure do |config|
   config.include RSpec::Rails::RequestExampleGroup, type: :request