@Test
    public void shouldLendBook_addBorrowersNameToList() {
        Book bookToTest = new Book("TestTitle", "2017", "Kimes", 1);
        List<String> expectedBorrwersList = new ArrayList<>();

        bookToTest.lendBook("Niedzielski");

        assertEquals(expectedBorrwersList.contains("Niedzielski"), ());

    }