Write unit tests for plugin scenarios not already tested for

[deborahgu]

Some unit tests have already been written to test for iFrame-based Plugins, PluginContainer, and ideally by this point the Direct Plugin and mixed Plugin Slots.

There are definitely some areas of the library that could use unit tests to confirm our assumptions.

Things worth testing include:

• Plugin Slot
  • it should return nothing if there’s no configuration and no default component
  • it should only return default component if there’s no configuration
  • it should return a React component given a config for one plugin
  • it should only return plugins that have a valid configuration (ie. missing key attributes for iFrame or Direct plugin)
• Plugin Container iFrame
  • it should return an iFrame with a React component when given a config
• Consolidate any mock objects (i.e. iframeConfig, directConfig) where possible