Feature Tests (Legacy)
We no longer actively add feature tests to /spec/system since we have added Cypress as a tool for our end-to-end testing. Hence, we are in the process of replicating the current /spec/system tests in Cypress and in the future we will only use Rails Feature Tests if for some reason a test cannot be implemented in Cypress due to any limitations. You can read more about our e2e testing.
Feature tests are tests from the perspective of the end-user.
In the Rails world, we sometimes refer to these as Feature or System tests. A tool called Capybara is included to help us simulate a human's actions inside of our tests.
Generally, we are simulating what a user could do from their web browser and ensuring that the app behaves as intended. When a feature is heavily reliant on interaction from a user via the browser, it's a good idea to write automated Feature tests to uncover any bugs that might not be apparent from manual testing.
It's important to note that Rails System tests can be fairly slow, so it's
better to focus on testing core functionality or pieces of your code that you
think might be prone to regressions. Another strategy we use to help us keep
Feature tests fast is :aggregate_failures. :aggregate_failures allows us
to make multiple assertions within a single test. The flag signals to Rspec to
run each assertion and then report all of the failures back to us rather than
just the first failure. This saves time because we only have to setup the
conditions for the spec once and then make all of our assertions instead of
setting up the conditions repeatedly for each individual assertion.
Feature tests can be found in the directory spec/system.
You can run all Feature tests with:
bundle exec rspec spec/system
To run an individual file you can use:
bundle exec rspec spec/system/user_views_a_reading_list_spec.rb
To run a specific test case you can use:
bundle exec rspec spec/system/user_views_a_reading_list_spec.rb:10
where 10 is the line number of the test case that you want to execute.
You can read the official guide Testing Rails Applications to learn more.
Test Flags​
When creating tests using Rspec we have the ability to add flags to those tests that will signal to Rspec to run certain commands before, after, or around the test example.
js: true Flag​
js: true indicates that we want the JavaScript on the page to be executed when
the page is rendered, and a headless chrome instance will be initialized to do
so (instead of the default
rack_test driver).
If you are debugging a js: true spec and want to see the browser, you can set
HEADLESS=false before running a spec:
HEADLESS=false bundle exec rspec spec/app/system