@Test
    public void shouldLendBook_decreaseNumberOfCopies() {
        Book bookToTest = new Book("TestTitle", "2017", "Kimes", 1);
        int expectedNumberOfCopies = 0;

        bookToTest.lendBook("Niedzielski");

        assertEquals(expectedNumberOfCopies, bookToTest.getNumberOfCopies());

    }

    @Test
    public void shouldLendBook_changeBookStatus() {
        Book bookToTest = new Book("TestTitle", "2017", "Kimes", 1);
        BookStatus expectedBookStatus = BookStatus.NON_AVAILABLE;

        bookToTest.lendBook("Niedzielski");

        assertEquals(expectedBookStatus, bookToTest.getEnumBookStatus());

    }

    @Test
    public void shouldLendBook_setBorrowersName() {
        Book bookToTest = new Book("TestTitle", "2017", "Kimes", 1);
        String expectedBorrowersName = "Niedzielski";

        bookToTest.lendBook("Niedzielski");

        assertEquals(expectedBorrowersName, bookToTest.getBorrowersName());

    }