openzeppelin-contracts/test/utils/introspection/ERC1820Implementer.test.js

const { expectRevert, singletons } = require('@openzeppelin/test-helpers');
const { bufferToHex, keccakFromString } = require('ethereumjs-util');

const { expect } = require('chai');

const ERC1820Implementer = artifacts.require('$ERC1820Implementer');

contract('ERC1820Implementer', function (accounts) {
  const [registryFunder, implementee, other] = accounts;

  const ERC1820_ACCEPT_MAGIC = bufferToHex(keccakFromString('ERC1820_ACCEPT_MAGIC'));

  beforeEach(async function () {
    this.implementer = await ERC1820Implementer.new();
    this.registry = await singletons.ERC1820Registry(registryFunder);

    this.interfaceA = bufferToHex(keccakFromString('interfaceA'));
    this.interfaceB = bufferToHex(keccakFromString('interfaceB'));
  });

  context('with no registered interfaces', function () {
    it('returns false when interface implementation is queried', async function () {
      expect(await this.implementer.canImplementInterfaceForAddress(this.interfaceA, implementee)).to.not.equal(
        ERC1820_ACCEPT_MAGIC,
      );
    });

    it('reverts when attempting to set as implementer in the registry', async function () {
      await expectRevert(
        this.registry.setInterfaceImplementer(implementee, this.interfaceA, this.implementer.address, {
          from: implementee,
        }),
        'Does not implement the interface',
      );
    });
  });

  context('with registered interfaces', function () {
    beforeEach(async function () {
      await this.implementer.$_registerInterfaceForAddress(this.interfaceA, implementee);
    });

    it('returns true when interface implementation is queried', async function () {
      expect(await this.implementer.canImplementInterfaceForAddress(this.interfaceA, implementee)).to.equal(
        ERC1820_ACCEPT_MAGIC,
      );
    });

    it('returns false when interface implementation for non-supported interfaces is queried', async function () {
      expect(await this.implementer.canImplementInterfaceForAddress(this.interfaceB, implementee)).to.not.equal(
        ERC1820_ACCEPT_MAGIC,
      );
    });

    it('returns false when interface implementation for non-supported addresses is queried', async function () {
      expect(await this.implementer.canImplementInterfaceForAddress(this.interfaceA, other)).to.not.equal(
        ERC1820_ACCEPT_MAGIC,
      );
    });

    it('can be set as an implementer for supported interfaces in the registry', async function () {
      await this.registry.setInterfaceImplementer(implementee, this.interfaceA, this.implementer.address, {
        from: implementee,
      });

      expect(await this.registry.getInterfaceImplementer(implementee, this.interfaceA)).to.equal(
        this.implementer.address,
      );
    });
  });
});