Add address to string conversion

CHANGELOG.md

@@ -5,6 +5,7 @@
  * `Clones`: optimize clone creation ([#3329](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3329))
  * `TimelockController`: Migrate `_call` to `_execute` and allow inheritance and overriding similar to `Governor`. ([#3317](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3317))
  * `CrossChainEnabledPolygonChild`: replace the `require` statement with the custom error `NotCrossChainCall`. ([#3380](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3380))
+ * `Strings`: add a new function `addressToHexString` that converts an `address` to its ASCII `string` hexadecimal representation. ([#3403](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3403))
 
 ## 4.6.0 (2022-04-26)
 

contracts/mocks/StringsMock.sol

@@ -16,4 +16,8 @@ contract StringsMock {
     function fromUint256HexFixed(uint256 value, uint256 length) public pure returns (string memory) {
         return Strings.toHexString(value, length);
     }
+
+    function fromAddressHex(address addr) public pure returns (string memory) {
+        return Strings.addressToHexString(addr);
+    }
 }

contracts/utils/Strings.sol

@@ -64,4 +64,11 @@ library Strings {
         require(value == 0, "Strings: hex length insufficient");
         return string(buffer);
     }
+
+    /**
+     * @dev Converts an `address` to its ASCII `string` hexadecimal representation.
+     */
+    function addressToHexString(address addr) internal pure returns (string memory) {
+        return toHexString(uint256(uint160(addr)));
+    }
 }

test/utils/Strings.test.js

@@ -56,4 +56,11 @@ contract('Strings', function (accounts) {
         .to.equal(web3.utils.toHex(constants.MAX_UINT256));
     });
   });
+
+  describe('from address - hex format', function () {
+    it('converts an address', async function () {
+      expect(web3.utils.toChecksumAddress(await this.strings.fromAddressHex(this.strings.address)))
+        .to.equal(this.strings.address.toString());
+    });
+  });
 });