Using database assertions

We have learned how to start up our application in a test environment, as well as how to write and run E2E tests for our application. This has taken us far toward verifying the behavior of our application, but how can we be sure that the stored data and database components are correct? The final aspect of E2E testing that will help us answer this question is database testing. Looking at the tests we have written so far, we notice two things:

• The database is typically initialized as empty, then the tables are torn down once the application shuts down. This has the advantage that we know there will be no persistent data that interferes with our tests, but it has the disadvantage of having to set up any required data as part of the test. For example, in our case, registering an available book requires a user ID, so we will have to create a user first before we do any book-related tasks. This can make our test suite running time longer.
• The items...