Add tests to bot.py

[ifosch]

Features to test:

• Basic creation of the Bot object with the following cases:
  • No admins
  • Single admin
  • Many admins
  • No plugins
  • Single plugin
  • Multiple plugins
• Bot.name and Bot.username, probably to be tested through logger mock
• Bot.start_message: Varying on the amount of plugins, like the constructor
• Bot.help_message, Bot.admin_help_message, and Bot.plugin_help_messages
• Bot.enabled_plugins and Bot.disabled_plugins
• Bot.start(bot, update)
• Bot.help(bot, update): Varying on the amount of plugins and admins, like the constructor
• Bot.settings(bot, update)
• Bot.enable_plugin(bot, update, args) and Bot.disable_plugin(bot, update, args), for these cases:
  • Not being an admin, it tells user can't enable/disable plugins
  • Not receiving a plugin name, it tells user a plugin name must be specified
  • When the plugin is enabled/disabled, it tells the user the plugin is not disabled/enabled
  • When the plugin is disabled/enabled, it enables/disables the plugin and tells the user it has been enabled/disabled
• Bot.run(): It starts polling

Fakes/spies to be implemented:

• logger
• Updater
• CommandHandler
• Dispatcher
• BotPlugins
• bot and update