text: const { BN, expectRevert } = require('@openzeppelin/test-helpers');
  
  const { expect } = require('chai');
  
  const ERC721URIStorageMock = artifacts.require('ERC721URIStorageMock');
  
  contract('ERC721URIStorage', function (accounts) {
    const [ owner ] = accounts;
  
    const name = 'Non Fungible Token';
    const symbol = 'NFT';
  
    const firstTokenId = new BN('5042');
    const nonExistentTokenId = new BN('13');
  
    beforeEach(async function () {
      this.token = await ERC721URIStorageMock.new(name, symbol);
    });
  
    describe('token URI', function () {
      beforeEach(async function () {
        await this.token.mint(owner, firstTokenId);
      });
  
      const baseURI = 'https://api.example.com/v1/';
      const sampleUri = 'mock://mytoken';
  
      it('it is empty by default', async function () {
        expect(await this.token.tokenURI(firstTokenId)).to.be.equal('');
      });
  
      it('reverts when queried for non existent token id', async function () {
        await expectRevert(
          this.token.tokenURI(nonExistentTokenId), 'ERC721URIStorage: URI query for nonexistent token',
        );
      });
  
      it('can be set for a token id', async function () {
        await this.token.setTokenURI(firstTokenId, sampleUri);
        expect(await this.token.tokenURI(firstTokenId)).to.be.equal(sampleUri);
      });
  
      it('reverts when setting for non existent token id', async function () {
        await expectRevert(
          this.token.setTokenURI(nonExistentTokenId, sampleUri), 'ERC721URIStorage: URI set of nonexistent token',
        );
      });
  
      it('base URI can be set', async function () {
        await this.token.setBaseURI(baseURI);
        expect(await this.token.baseURI()).to.equal(baseURI);
      });
  
      it('base URI is added as a prefix to the token URI', async function () {
        await this.token.setBaseURI(baseURI);
        await this.token.setTokenURI(firstTokenId, sampleUri);
  
        expect(await this.token.tokenURI(firstTokenId)).to.be.equal(baseURI + sampleUri);
      });
  
      it('token URI can be changed by changing the base URI', async function () {
        await this.token.setBaseURI(baseURI);
        await this.token.setTokenURI(firstTokenId, sampleUri);
  
        const newBaseURI = 'https://api.example.com/v2/';
        await this.token.setBaseURI(newBaseURI);
        expect(await this.token.tokenURI(firstTokenId)).to.be.equal(newBaseURI + sampleUri);
      });
  
      it('tokenId is appended to base URI for tokens with no URI', async function () {
        await this.token.setBaseURI(baseURI);
  
        expect(await this.token.tokenURI(firstTokenId)).to.be.equal(baseURI + firstTokenId);
      });
  
      it('tokens without URI can be burnt ', async function () {
        await this.token.burn(firstTokenId, { from: owner });
  
        expect(await this.token.exists(firstTokenId)).to.equal(false);
        await expectRevert(
          this.token.tokenURI(firstTokenId), 'ERC721URIStorage: URI query for nonexistent token',
        );
      });
  
      it('tokens with URI can be burnt ', async function () {
        await this.token.setTokenURI(firstTokenId, sampleUri);
  
        await this.token.burn(firstTokenId, { from: owner });
  
        expect(await this.token.exists(firstTokenId)).to.equal(false);
        await expectRevert(
          this.token.tokenURI(firstTokenId), 'ERC721URIStorage: URI query for nonexistent token',
        );
      });
    });
  });
  