Missing tests in 6.3.3

[kantuni]

The 2nd paragraph of section 6.3.3 says

Here we can benefit from the test coverage we've obtained through tests we wrote earlier in the chapter. We already have tests that verify the following:

• When the photos load, the first one gets selected.
• Whenever update receives a ClickedPhoto message, that photo becomes selected.

Neither of these tests were provided earlier in the chapter.