openzeppelin-contracts/test/token/ERC721/ERC721MintBurn.behavior.js

const { assertRevert } = require('../../helpers/assertRevert');
const BigNumber = web3.BigNumber;

require('chai')
  .use(require('chai-bignumber')(BigNumber))
  .should();

function shouldBehaveLikeMintAndBurnERC721 (accounts) {
  const firstTokenId = 1;
  const secondTokenId = 2;
  const unknownTokenId = 3;
  const creator = accounts[0];
  const ZERO_ADDRESS = '0x0000000000000000000000000000000000000000';

  describe('like a mintable and burnable ERC721', function () {
    beforeEach(async function () {
      await this.token.mint(creator, firstTokenId, { from: creator });
      await this.token.mint(creator, secondTokenId, { from: creator });
    });

    describe('mint', function () {
      const to = accounts[1];
      const tokenId = unknownTokenId;
      let logs = null;

      describe('when successful', function () {
        beforeEach(async function () {
          const result = await this.token.mint(to, tokenId);
          logs = result.logs;
        });

        it('assigns the token to the new owner', async function () {
          (await this.token.ownerOf(tokenId)).should.be.equal(to);
        });

        it('increases the balance of its owner', async function () {
          (await this.token.balanceOf(to)).should.be.bignumber.equal(1);
        });

        it('emits a transfer event', async function () {
          logs.length.should.be.equal(1);
          logs[0].event.should.be.equal('Transfer');
          logs[0].args._from.should.be.equal(ZERO_ADDRESS);
          logs[0].args._to.should.be.equal(to);
          logs[0].args._tokenId.should.be.bignumber.equal(tokenId);
        });
      });

      describe('when the given owner address is the zero address', function () {
        it('reverts', async function () {
          await assertRevert(this.token.mint(ZERO_ADDRESS, tokenId));
        });
      });

      describe('when the given token ID was already tracked by this contract', function () {
        it('reverts', async function () {
          await assertRevert(this.token.mint(accounts[1], firstTokenId));
        });
      });
    });

    describe('burn', function () {
      const tokenId = firstTokenId;
      const sender = creator;
      let logs = null;

      describe('when successful', function () {
        beforeEach(async function () {
          const result = await this.token.burn(tokenId, { from: sender });
          logs = result.logs;
        });

        it('burns the given token ID and adjusts the balance of the owner', async function () {
          await assertRevert(this.token.ownerOf(tokenId));
          (await this.token.balanceOf(sender)).should.be.bignumber.equal(1);
        });

        it('emits a burn event', async function () {
          logs.length.should.be.equal(1);
          logs[0].event.should.be.equal('Transfer');
          logs[0].args._from.should.be.equal(sender);
          logs[0].args._to.should.be.equal(ZERO_ADDRESS);
          logs[0].args._tokenId.should.be.bignumber.equal(tokenId);
        });
      });

      describe('when there is a previous approval', function () {
        beforeEach(async function () {
          await this.token.approve(accounts[1], tokenId, { from: sender });
          const result = await this.token.burn(tokenId, { from: sender });
          logs = result.logs;
        });

        it('clears the approval', async function () {
          (await this.token.getApproved(tokenId)).should.be.equal(ZERO_ADDRESS);
        });
      });

      describe('when the given token ID was not tracked by this contract', function () {
        it('reverts', async function () {
          await assertRevert(this.token.burn(unknownTokenId, { from: creator }));
        });
      });
    });
  });
}

module.exports = {
  shouldBehaveLikeMintAndBurnERC721,
};