The code in Listing 7.26 arranges to insert a div tag for each element in the flash, with a CSS class indicating the type of message. For example, if flash[:success] = "Welcome to the Sample App!", then the code

will produce this HTML:

(Note that the key :success is a symbol, but Embedded Ruby automatically converts it to the string "success" before inserting it into the template.) The reason we iterate through all possible key/value pairs is so that we can include other kinds of flash messages. For example, in Section 8.1.5 we’ll see flash[:error] used to indicate a failed signin attempt.

11 Writing a test for the right flash message is left as an exercise (Section 7.6), and we can get the test to pass by assigning flash[:success] a welcome message in the create action, as shown in Listing 7.27.