Empty string in smart contract (#5648)

* Add test

* Update packages/web3-eth-contract/test/integration/contract_empty_string.test.ts

Co-authored-by: Muhammad Altabba <[email protected]>

* Change name of test

Co-authored-by: Muhammad Altabba <[email protected]>

Author: nikoulai

fixtures/build/MyContract.json

@@ -0,0 +1,22 @@
+{
+	"abi": [
+		{
+			"inputs": [],
+			"name": "getAttr",
+			"outputs": [
+				{
+					"internalType": "string",
+					"name": "",
+					"type": "string"
+				}
+			],
+			"stateMutability": "view",
+			"type": "function"
+		}
+	],
+	"evm": {
+		"bytecode": {
+			"object": "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"
+		}
+	}
+}

fixtures/build/MyContract.ts

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+/*
+This file is part of web3.js.
+
+web3.js is free software: you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+web3.js is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License
+along with web3.js.  If not, see <http://www.gnu.org/licenses/>.
+*/
+export const MyContractAbi = [
+	{
+		inputs: [],
+		name: 'getAttr',
+		outputs: [{ internalType: 'string', name: '', type: 'string' }],
+		stateMutability: 'view',
+		type: 'function',
+	},
+] as const;
+export const MyContractBytecode =
+	'0x608060405234801561001057600080fd5b50610228806100206000396000f3fe608060405234801561001057600080fd5b506004361061002b5760003560e01c8063f540c8ba14610030575b600080fd5b61003861004e565b6040516100459190610170565b60405180910390f35b60606000805461005d906101c1565b80601f0160208091040260200160405190810160405280929190818152602001828054610089906101c1565b80156100d65780601f106100ab576101008083540402835291602001916100d6565b820191906000526020600020905b8154815290600101906020018083116100b957829003601f168201915b5050505050905090565b600081519050919050565b600082825260208201905092915050565b60005b8381101561011a5780820151818401526020810190506100ff565b60008484015250505050565b6000601f19601f8301169050919050565b6000610142826100e0565b61014c81856100eb565b935061015c8185602086016100fc565b61016581610126565b840191505092915050565b6000602082019050818103600083015261018a8184610137565b905092915050565b7f4e487b7100000000000000000000000000000000000000000000000000000000600052602260045260246000fd5b600060028204905060018216806101d957607f821691505b6020821081036101ec576101eb610192565b5b5091905056fea264697066735822122061f485ab43edfa5bd740bc1f3dd0d643813a4bd2457119e6578414d7389fbd8964736f6c63430008100033';

fixtures/contracts/MyContract.sol

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+// SPDX-License-Identifier: GNU
+
+pragma solidity ^0.8.13;
+
+contract MyContract {
+	string private myAttribute;
+
+	function getAttr() public view returns (string memory) {
+		return myAttribute;
+	}
+}

packages/web3-eth-contract/test/fixtures/MyContract.json

@@ -0,0 +1 @@
+../../../../fixtures/build/MyContract.json

packages/web3-eth-contract/test/fixtures/MyContract.ts

@@ -0,0 +1 @@
+../../../../fixtures/build/MyContract.ts

packages/web3-eth-contract/test/integration/contract_empty_string.test.ts

@@ -0,0 +1,48 @@
+/*
+This file is part of web3.js.
+
+web3.js is free software: you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+web3.js is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License
+along with web3.js.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+import { Contract } from '../../src';
+import { getSystemTestProvider, createTempAccount } from '../fixtures/system_test_utils';
+import { MyContractAbi, MyContractBytecode } from '../fixtures/MyContract';
+
+describe('request empty string from contract', () => {
+	let contract: Contract<typeof MyContractAbi>;
+	let deployOptions: Record<string, unknown>;
+	let sendOptions: Record<string, unknown>;
+	beforeAll(async () => {
+		contract = new Contract(MyContractAbi, undefined, {
+			provider: getSystemTestProvider(),
+		});
+		const acc = await createTempAccount();
+
+		deployOptions = {
+			data: MyContractBytecode,
+			arguments: [],
+		};
+
+		sendOptions = { from: acc.address, gas: '1000000' };
+	});
+
+	it('should fetch empty string', async () => {
+		const deployedContract = await contract.deploy(deployOptions).send(sendOptions);
+
+		const attribute = await deployedContract.methods.getAttr().call();
+
+		expect(attribute).toHaveLength(0);
+		expect(attribute).toBe('');
+	});
+});