@Test public void testOneBorrowedBook() throws Exception {

    List<BookBorrowing> borrowedBooks =  this.bookBorrowingRepository.borrowedBooks();
    assertThat(borrowedBooks.size(), is(1));
    BookBorrowing bookBorrowing = borrowedBooks.get(0);
    assertThat(bookBorrowing, equalTo(this.testBookBorrowing));
}