Testing

Rails comes with a robust test suite. Let’s write a test to ensure that the correct number of emails are sent when a product is back in stock.

Fixtures

When you generate a model using Rails, it automatically creates a corresponding fixture file in the test/fixtures directory.

Fixtures are predefined sets of data that populate your test database before running tests. They allow you to define records with easy-to-remember names, making it simple to access them in your tests.

This file will be empty by default - you need to populate it with fixtures for your tests.

Let’s update the product fixtures file at test/fixtures/products.yml with the following:

tshirt:
  name: T-Shirt
  inventory_count: 15

And for subscribers, let’s add these two fixtures to test/fixtures/subscribers.yml:

david:
  product: tshirt
  email: david@example.org

chris:
  product: tshirt
  email: chris@example.org

You’ll notice that we can reference the Product fixture by name here. Rails associates this automatically for us in the database so we don’t have to manage record IDs and associations in tests.

These fixtures will be automatically inserted into the database when we run our test suite.