The unit tests must test code that consumes sealed classes.
You need to create, maintain, and inject dependencies in the unit tests.
Which isolation method should you use?

You need to test the AccountBalance method.
Which unit test should you use?

The application throws and handles exceptions when it runs.
You need to examine the state of the application when exceptions are thrown.
What should you do?
The application must be compatible with multiple browsers. A user can search the website for news articles. You must track the page number that the user is viewing in search results.
You need to program the location for storing state information about the user's search.
What should you do?
The application must handle web server failures gracefully. The servers in the farm must share the state information.
You need to persist the application state during the session.
What should you implement?