Functional Testing

Unit testing checks on data validation and simple connections, but there’s a lot more happening in the typical Rails application. Controllers are the key piece connecting data to users, supporting a number of complex interactions that need more sophisticated testing than checking validation or data. Controllers need functional tests that can examine the actions they were supposed to perform. In Rails, these tests are defined in files in the tests/functional directory.


Functional testing, in Rails’ unique way of performing it, is only about testing controllers. Again, if you have previous experience with testing in other environments or move on later to other environments, this can be confusing.

Unlike the unit tests generated by Rails, which did nothing, the functional tests created by the REST scaffolding at least provide a basic structure that’s useful. (The functional tests created for ordinary controllers are a placeholder like the unit test one.) The courses_controller_test.rb file shown in Example 12-12 is capable of calling the REST methods and making sure they work—except, of course, the fixtures generated by the scaffolding will create problems.

Example 12-12. An almost-functional functional test set generated by Rails for the courses controller

require 'test_helper' class CoursesControllerTest < ActionController::TestCase def test_should_get_index get :index assert_response :success assert_not_nil assigns(:courses) end def test_should_get_new get :new ...

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