find_and_read_book(Isbn) ->
    {ok, Book} = library:lookup({isbn, Isbn}),
    media:view_book(Book).

take_book_test() ->
    Mock = em:new(),
    ISBN = '978-3-596-17577-2',

    %% expectations:
    em:strict(Mock, library, lookup, [{isbn, ISBN}], {return, {ok, some_book_id}}).
    em:strict(Mock, media, view_book, [some_book_id], {return, ok}),
    em:replay(Mock),

    %% Run code under test:
    production:find_and_read_book(ISBN),
    %% assertions:
    em:verify(Mock).

{em, "7.2.6"}