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// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
import { expect } from "./expect.ts";import type { MatcherContext, Tester } from "./_types.ts";
declare module "./_types.ts" {  interface Expected {    toEqualBook: (expected: unknown) => ExtendMatchResult;  }}
class Author {  public name: string;
  constructor(name: string) {    this.name = name;  }}
class Book {  public name: string;  public authors: Array<Author>;
  constructor(name: string, authors: Array<Author>) {    this.name = name;    this.authors = authors;  }}
const areAuthorsEqual: Tester = (a: unknown, b: unknown) => {  const isAAuthor = a instanceof Author;  const isBAuthor = b instanceof Author;
  if (isAAuthor && isBAuthor) {    return a.name === b.name;  } else if (isAAuthor === isBAuthor) {    return undefined;  } else {    return false;  }};
const areBooksEqual: Tester = function (  this: MatcherContext,  a: unknown,  b: unknown,  customTesters: Tester[],) {  const isABook = a instanceof Book;  const isBBook = b instanceof Book;
  if (isABook && isBBook) {    return (a.name === b.name &&      this.equal(a.authors, b.authors, { customTesters: customTesters }));  } else if (isABook === isBBook) {    return undefined;  } else {    return false;  }};
expect.addEqualityTesters([  areAuthorsEqual,  areBooksEqual,]);
expect.extend({  toEqualBook(context, expected) {    const actual = context.value as Book;    const result = context.equal(expected, actual, {      customTesters: context.customTesters,    });
    return {      message: () =>        `Expected Book object: ${expected.name}. Actual Book object: ${actual.name}`,      pass: result,    };  },});
Deno.test("expect.extend() api test case", () => {  const book1a = new Book("Book 1", [    new Author("Author 1"),    new Author("Author 2"),  ]);  const book1b = new Book("Book 1", [    new Author("Author 1"),    new Author("Author 2"),  ]);  const book2 = new Book("Book 2", [    new Author("Author 1"),    new Author("Author 2"),  ]);
  expect(book1a).toEqualBook(book1b);  expect(book1a).not.toEqualBook(book2);  expect(book1a).not.toEqualBook(1);  expect(book1a).not.toEqualBook(null);});