Inject the entity type manager service into the ArticleRepository, and
use it to load and return all nodes.
This fails as not enough arguments are passed to the article repository
service from the container.
Add the `getAll()` method to the ArticleRepository, ensuring that it
returns an array.
This returns as 0 articles are returned, but 3 are expected in the
assertion.
Add the BlogPageController that is referenced within
`my_module.routing.yml`.
We will need to return a render array, but for now let’s return an empty
array.
The test now passes as we are getting the expected response code.
