Feature/erc20 erc165 #1073

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## 2.2.0 (unreleased)
 
 ### New features:
+ * `ERC20`, `ERC20Burnable`, `ERC20Detailed`: added ERC165 implementations
  * `ERC20`: added internal `_approve(address owner, address spender, uint256 value)`, allowing derived contracts to set the allowance of arbitrary accounts.
  * `ERC20Metadata`: added internal `_setTokenURI(string memory tokenURI)`.
 

contracts/token/ERC20/ERC20.sol

@@ -2,6 +2,7 @@ pragma solidity ^0.5.2;
 
 import "./IERC20.sol";
 import "../../math/SafeMath.sol";
+import "../../introspection/ERC165.sol";
 
 /**
  * @title Standard ERC20 token
@@ -15,7 +16,7 @@ import "../../math/SafeMath.sol";
  * all accounts just by listening to said events. Note that this isn't required by the specification, and other
  * compliant implementations may not do it.
  */
-contract ERC20 is IERC20 {
+contract ERC20 is ERC165, IERC20 {
     using SafeMath for uint256;
 
     mapping (address => uint256) private _balances;
@@ -24,6 +25,23 @@ contract ERC20 is IERC20 {
 
     uint256 private _totalSupply;
 
+    bytes4 private constant _INTERFACE_ID_ERC20 = 0x36372b07;
+    /*
+     * 0x36372b07 ===
+     *     bytes4(keccak256('transfer(address,uint256)')) ^
+     *     bytes4(keccak256('approve(address,uint256)')) ^
+     *     bytes4(keccak256('transferFrom(address,address,uint256)')) ^
+     *     bytes4(keccak256('totalSupply()')) ^
+     *     bytes4(keccak256('balanceOf(address)')) ^
+     *     bytes4(keccak256('allowance(address,address)'))
+     */
+
+    constructor()
+    public
+    {
+        _registerInterface(_INTERFACE_ID_ERC20);
+    }
+
     /**
      * @dev Total number of tokens in existence
      */

contracts/token/ERC20/ERC20Burnable.sol

@@ -1,12 +1,24 @@
 pragma solidity ^0.5.2;
 
 import "./ERC20.sol";
+import "../../introspection/ERC165.sol";
 
 /**
  * @title Burnable Token
  * @dev Token that can be irreversibly burned (destroyed).
  */
-contract ERC20Burnable is ERC20 {
+contract ERC20Burnable is ERC165, ERC20 {
+    bytes4 private constant _INTERFACE_ID_ERC20_BURNABLE = 0x3b5a0bf8;
+    /*
+     * 0x3b5a0bf8 ===
+     *     bytes4(keccak256('burn(uint256)') ^
+     *     bytes4(keccak256('burnFrom(address,uint256)'))
+     */
+
+    constructor () public {
+        _registerInterface(_INTERFACE_ID_ERC20_BURNABLE);
+    }
+
     /**
      * @dev Burns a specific amount of tokens.
      * @param value The amount of token to be burned.

contracts/token/ERC20/ERC20Detailed.sol

@@ -1,22 +1,32 @@
 pragma solidity ^0.5.2;
 
 import "./IERC20.sol";
+import "../../introspection/ERC165.sol";
 
 /**
  * @title ERC20Detailed token
  * @dev The decimals are only for visualization purposes.
  * All the operations are done using the smallest and indivisible token unit,
  * just as on Ethereum all the operations are done in wei.
  */
-contract ERC20Detailed is IERC20 {
+contract ERC20Detailed is ERC165, IERC20 {
     string private _name;
     string private _symbol;
     uint8 private _decimals;
 
+    bytes4 private constant _INTERFACE_ID_ERC20_DETAILED = 0xa219a025;
+    /*
+     * 0xa219a025 ===
+     *     bytes4(keccak256('name()') ^
+     *     bytes4(keccak256('symbol()')) ^
+     *     bytes4(keccak256('decimals()'))
+     */
+
     constructor (string memory name, string memory symbol, uint8 decimals) public {
         _name = name;
         _symbol = symbol;
         _decimals = decimals;
+        _registerInterface(_INTERFACE_ID_ERC20_DETAILED);
     }
 
     /**

test/introspection/SupportsInterface.behavior.js

@@ -4,6 +4,23 @@ const INTERFACE_IDS = {
   ERC165: makeInterfaceId([
     'supportsInterface(bytes4)',
   ]),
+  ERC20: makeInterfaceId([
+    'transfer(address,uint256)',
+    'approve(address,uint256)',
+    'transferFrom(address,address,uint256)',
+    'totalSupply()',
+    'balanceOf(address)',
+    'allowance(address,address)',
+  ]),
+  ERC20Burnable: makeInterfaceId([
+    'burn(uint256)',
+    'burnFrom(address,uint256)',
+  ]),
+  ERC20Detailed: makeInterfaceId([
+    'name()',
+    'symbol()',
+    'decimals()',
+  ]),
   ERC721: makeInterfaceId([
     'balanceOf(address)',
     'ownerOf(uint256)',

test/token/ERC20/ERC20.test.js

@@ -2,6 +2,7 @@ const { BN, constants, expectEvent, shouldFail } = require('openzeppelin-test-he
 const { ZERO_ADDRESS } = constants;
 
 const ERC20Mock = artifacts.require('ERC20Mock');
+const { shouldSupportInterfaces } = require('../../introspection/SupportsInterface.behavior');
 
 contract('ERC20', function ([_, initialHolder, recipient, anotherAccount]) {
   const initialSupply = new BN(100);
@@ -559,4 +560,9 @@ contract('ERC20', function ([_, initialHolder, recipient, anotherAccount]) {
       });
     });
   }
+
+  shouldSupportInterfaces([
+    'ERC165',
+    'ERC20',
+  ]);
 });

test/token/ERC20/ERC20Burnable.test.js

@@ -2,6 +2,7 @@ const { BN } = require('openzeppelin-test-helpers');
 
 const { shouldBehaveLikeERC20Burnable } = require('./behaviors/ERC20Burnable.behavior');
 const ERC20BurnableMock = artifacts.require('ERC20BurnableMock');
+const { shouldSupportInterfaces } = require('../../introspection/SupportsInterface.behavior');
 
 contract('ERC20Burnable', function ([_, owner, ...otherAccounts]) {
   const initialBalance = new BN(1000);
@@ -11,4 +12,9 @@ contract('ERC20Burnable', function ([_, owner, ...otherAccounts]) {
   });
 
   shouldBehaveLikeERC20Burnable(owner, initialBalance, otherAccounts);
+
+  shouldSupportInterfaces([
+    'ERC165',
+    'ERC20Burnable',
+  ]);
 });

test/token/ERC20/ERC20Detailed.test.js

@@ -1,25 +1,31 @@
 const { BN } = require('openzeppelin-test-helpers');
 
 const ERC20DetailedMock = artifacts.require('ERC20DetailedMock');
+const { shouldSupportInterfaces } = require('../../introspection/SupportsInterface.behavior');
 
 contract('ERC20Detailed', function () {
   const _name = 'My Detailed ERC20';
   const _symbol = 'MDT';
   const _decimals = new BN(18);
 
   beforeEach(async function () {
-    this.detailedERC20 = await ERC20DetailedMock.new(_name, _symbol, _decimals);
+    this.token = await ERC20DetailedMock.new(_name, _symbol, _decimals);
   });
 
   it('has a name', async function () {
-    (await this.detailedERC20.name()).should.be.equal(_name);
+    (await this.token.name()).should.be.equal(_name);
   });
 
   it('has a symbol', async function () {
-    (await this.detailedERC20.symbol()).should.be.equal(_symbol);
+    (await this.token.symbol()).should.be.equal(_symbol);
   });
 
   it('has an amount of decimals', async function () {
-    (await this.detailedERC20.decimals()).should.be.bignumber.equal(_decimals);
+    (await this.token.decimals()).should.be.bignumber.equal(_decimals);
   });
+
+  shouldSupportInterfaces([
+    'ERC165',
+    'ERC20Detailed',
+  ]);
 });