As mentioned in the previous section, table view cells should be dequeued. To make sure that this happens, we need a test. The dequeuing is done by calling the dequeueReusableCell(withIdentifier:for:) method on the table view. The table view then checks whether there is a cell that can be reused. If not, it creates a new cell and returns it. We are going to use a table view mock to register when the method is called.
In Swift, classes can be defined within other classes. In the case of mocks, this is useful because, this way, the mocks are only visible and accessible at the point where they are needed.
Add the following code to ItemListDataProviderTests.swift, outside of the ItemListDataProviderTests class:
extension ItemListDataProviderTests ...