public boolean equals(Object obj) {
if (!(obj instanceof Book)) return false;
Book book = (Book) obj;
return (this.ISBN == book.getISBN()
&& this.getTitle().equals(book.getTitle())
&& this.getAuthor().equals(book.getAuthor())
&& this.getPrice() == book.getPrice());
}
@Test
public void testBookShouldHaveISBNNumber() throws Exception {
Book book = new Book("TDD", 22341);
assertEquals(22341, book.getISBN());
}
