Testing can spare you much of the work you learned to do in the previous chapter, replacing spot-check debugging with more structured and thorough repetitive testing. Ruby culture places a high value on testing, and Ruby and Rails have grown up with agile development methods where testing is assumed to be a normal part of development. While testing is a complicated subject worthy of a book or several, it’s definitely worthwhile to start including tests early in your project development, even while you’re still learning the Rails landscape.
Rails provides a number of facilities for creating and managing tests. This chapter will explore Rails’ basic testing setup and note some options for building more advanced test platforms. (Examples for this chapter are in ch12/students006.)
Many developers use RSpec, an additional framework for testing noted at the end of this chapter, but it’s worth understanding the foundations provided in Rails itself.
Up to this point, all the code in this book has been run in development mode. Rails supports three different environments for running applications. Each of them has its own database, as well as its own settings:
Development is the default mode. In development mode, Rails loads and reloads code every time a request is made, making it easy for you to see changes without a cache getting in the way. It’s also typical to use SQLite as the database, as Rails isn’t going to be working at high speed anyway.