Resolver code for AuthorOps

authorOps.js

const addBook = (book, authorId) => {
    console.log("addBook", book, authorId)
    return new Promise((resolve, reject) => {
        book.authorId = authorId
        books.push(book)
        resolve(books.length)
    })
}

const removeBook = (book, authorId) => {
    return new Promise((resolve, reject) => {
        books = books.filter(b => b.ISBN !== book.ISBN && b.authorId === authorId);
        resolve(books.length)
    })
}

const updateBook = (book, authorId) => {
    return new Promise((resolve, reject) => {
        let old = books.find(b => b.ISBN === book.ISBN && b.authorId === authorId);
        if (!old) {
            reject(`Book with ISBN = ${book.ISBN} not found`)
            return
        }
        resolve(Object.assign(old, book))
    })
}

const AuthorOps = (authorId) => ({
    addBook: ({
        input
    }) => addBook(input, authorId),
    removeBook: ({
        input
    }) => removeBook(input, authorId),
    updateBook: ({
        input
    }) => updateBook(input, authorId)
})