But it is kind of verbose, and it’s also a lot slower, so I can understand why the model test might be preferred.

Why does test suite performance matter? First of all, testing is a part of a developer's feedback loop (see @searls talk) and, secondly, it is a part of a deployment cycle.

These tests should be isolated as much as possible. For example, model methods that don’t do anything with the database shouldn’t need a DB record. Classes that don’t need database records should use stubs/doubles as much as possible.

A common cause of a large number of created factories is factory cascades, which result when factories create and recreate associations.

Test speed GitLab has a massive test suite that, without parallelization, can take hours to run. It’s important that we make an effort to write tests that are accurate and effective as well as fast.

:js is particularly important to avoid. This must only be used if the feature test requires JavaScript reactivity in the browser. Using a headless browser is much slower than parsing the HTML response from the app.

Use Factory Doctor to find cases where database persistence is not needed in a given test.

It is not customary in Rails to run the full test suite before pushing changes. The railties test suite in particular takes a long time, and takes an especially long time if the source code is mounted in /vagrant as happens in the recommended workflow with the rails-dev-box.As a compromise, test what your code obviously affects, and if the change is not in railties, run the whole test suite of the affected component. If all tests are passing, that's enough to propose your contribution.