借阅系统

本课属于 Coddy Python 学习旅程的“面向对象编程”单元。第 57 课，共 64 课。

挑战

中等

在这个挑战中，你将为图书馆管理系统添加借书功能。

编辑 library.py，并按照 TODO 注释实现 borrow_book 方法。

其他文件已提供给你，并且已锁定：

book.py：你在上一个挑战中编写的 Book 类
user.py：包含 user_id、name 和 books_borrowed 的 User 类
driver.py：使用测试场景测试你的实现

borrow_book(book_isbn, user_id) 必须恰好返回以下其中一个值："Book not found"、"User not found"、"Book is not available" 或 "Book borrowed successfully"。

亲手试试

from book import Book
from user import User
from library import Library

# 综合测试用例处理程序
test_case = input()

# 基本功能测试
if test_case == "borrow_success":
    library = Library("Community Library")
    
    # 添加图书和用户
    book = Book("The Great Gatsby", "F. Scott Fitzgerald", "123456")
    library.add_book(book)
    
    user = User("U001", "Alice")
    library.add_user(user)
    
    # 借阅图书
    result = library.borrow_book("123456", "U001")
    print(result)
    print(f"Book available: {book.available}")
    print(f"Books borrowed by user: {len(user.books_borrowed)}")

elif test_case == "book_not_found":
    library = Library("Community Library")
    user = User("U001", "Alice")
    library.add_user(user)
    
    result = library.borrow_book("nonexistent", "U001")
    print(result)

elif test_case == "user_not_found":
    library = Library("Community Library")
    book = Book("The Great Gatsby", "F. Scott Fitzgerald", "123456")
    library.add_book(book)
    
    result = library.borrow_book("123456", "nonexistent")
    print(result)
    
elif test_case == "book_not_available":
    library = Library("Community Library")
    
    # 添加图书和用户
    book = Book("The Great Gatsby", "F. Scott Fitzgerald", "123456")
    book.available = False  # 图书已被借出
    library.add_book(book)
    
    user = User("U001", "Alice")
    library.add_user(user)
    
    # 尝试借阅不可借的图书
    result = library.borrow_book("123456", "U001")
    print(result)

# 边界情况和其他测试
elif test_case == "multiple_books":
    library = Library("Community Library")
    user = User("U001", "Alice")
    library.add_user(user)
    
    # 创建多本图书
    books = [
        Book("Book 1", "Author 1", "111"),
        Book("Book 2", "Author 2", "222"),
        Book("Book 3", "Author 3", "333")
    ]
    
    for book in books:
        library.add_book(book)
    
    # 借阅多本图书
    results = []
    for book in books:
        results.append(library.borrow_book(book.isbn, "U001"))
    
    for result in results:
        print(result)
    
    print(f"Total books borrowed: {len(user.books_borrowed)}")

elif test_case == "multiple_users":
    library = Library("Community Library")
    book = Book("Popular Book", "Famous Author", "999")
    library.add_book(book)
    
    # 创建多个用户
    users = [
        User("U001", "Alice"),
        User("U002", "Bob"),
        User("U003", "Charlie")
    ]
    
    for user in users:
        library.add_user(user)
    
    # 让不同用户尝试借阅同一本书
    result1 = library.borrow_book("999", "U001")
    result2 = library.borrow_book("999", "U002")  # 应该会失败
    
    print(result1)
    print(result2)
    print(f"Book's borrower: {book.borrower.name}")

elif test_case == "return_book":
    library = Library("Community Library")
    book = Book("The Great Gatsby", "F. Scott Fitzgerald", "123456")
    library.add_book(book)
    
    user = User("U001", "Alice")
    library.add_user(user)
    
    # 借阅这本书
    borrow_result = library.borrow_book("123456", "U001")
    print(borrow_result)
    
    # 检查图书状态
    print(f"Book available: {book.available}")
    print(f"Book borrower: {book.borrower.name}")
    print(f"User's borrowed books: {len(user.books_borrowed)}")
    print(f"First borrowed book title: {user.books_borrowed[0].title}")

elif test_case == "empty_library":
    library = Library("Empty Library")
    result = library.borrow_book("any_isbn", "any_user_id")
    print(result)

elif test_case == "borrower_reference":
    library = Library("Community Library")
    book = Book("The Great Gatsby", "F. Scott Fitzgerald", "123456")
    library.add_book(book)
    
    user = User("U001", "Alice")
    library.add_user(user)
    
    # 借阅这本书
    library.borrow_book("123456", "U001")
    
    # 检查引用关系
    print(f"Book's borrower name: {book.borrower.name}")
    print(f"First book in user's borrowed list: {user.books_borrowed[0].title}")