Part 3: Code Coverage

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When we cover unit testing, we will learn about code coverage, the percentage of your app’s code that is exercised by tests. As we will learn, there are many ways to measure code coverage, but this assignment has preinstalled a library called SimpleCov that measures “statement coverage”–essentially, which lines of your app were at least touched by your tests.

You can see that the first two lines of features/support/env.rb (which Cucumber loads automatically on each run) start the SimpleCov test coverage measurement.

Each time you run your tests (whether Cucumber acceptance tests or RSpec unit/module tests), SimpleCov generates a report in a directory named coverage/. To see the results, open coverage/index.html after a test run, and click on the name of any files in your app to see which lines were covered by your tests. Alternatively, on Codio, right click coverage/index.html and click Preview Static

What Cucumber scenarios would you have to add in order to cover the non-covered lines?

You can add a simple scenario for creating a movie and a simple scenario for destroying a movie. However, the current controller doesn't do any error checking if creation or deletion fails. If that code were added to the controller, you would either need multiple scenarios (to cover both happy and sad paths) or you would need to write more detailed RSpec tests to cover the corner cases. The RSpec assignments will show you how to do that.

If your test coverage isn’t already at 90%, add scenarios and steps to cover the gaps as indicated by SimpleCov. You will get 100% credit by getting at least 90% code coverage.