Adding 'Search Engines Indexing' Section [ci skip]
… of #15215 [ci skip]
…n uses a concept of default scope in its example before it is introduced in the following section titled `Applying a default scope`. It makes more sense to switch the ordering to introduce default scopes (`Applying a default scope`) first and then go into `Merging of scopes` section where it is used.
Two big features that are only barely related in the same guide. Seems bad. I did not check references to these guides yet, so some links may need to be updated.
Change the default test locations to avoid confusion around the common testing terms "unit" and "functional". Add new rake tasks for the new locations, while maintaining backwards compatibility with the old rake tasks. New testing locations are as follows: app/models -> test/models (was test/units) app/helpers -> test/helpers (was test/units/helpers) app/controllers -> test/controllers (was test/functional) app/mailers -> test/mailers (was test/functional)