Finally, as a security precaution, we’ll test for a length validation on passwords, requiring that they be at least six characters long:

Putting together all the tests above gives Listing 6.29.

As noted in Box 6.3, let memoizes its value, so that the first nested describe block in Listing 6.29 invokes let to retrieve the user from the database using find_by_email,
but the second describe block doesn’t hit the database a second time.