Calling a solidity payable function with etherjs - solidity

Question

I have a basic Solidity smart contract:
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
contract TestContract {
uint256 public _blockTimestamp;
function accumulated() public payable returns (uint256) {
_blockTimestamp = block.timestamp;
return 1;
}
}
And using remix IDE I can compile it and check the value of _blockTimestamp changing after executing the accumulated function.
Now, I can deploy the contract and check the value of the public variable without any problem with etherjs:
const provider = new providers.JsonRpcProvider(getEnv('RINKEBY_NODE_URL'));
const wallet = new Wallet(getEnv('ROPSTEN_PRIVATE_KEY'), provider);
const TestContract = TestContract__factory.connect(getEnv('TEST_CONTRACT'), provider);
const _blockTimestamp = await NFTLTokenContract._blockTimestamp();
The problem is when I try to execute the function accumulated. Being a payable function I need a signer:
const provider = new providers.JsonRpcProvider(getEnv('RINKEBY_NODE_URL'));
const wallet = new Wallet(getEnv('ROPSTEN_PRIVATE_KEY'), provider);
const TestContract = TestContract__factory.connect(getEnv('TEST_CONTRACT'), provider);
const _blockTimestamp = await TestContract._blockTimestamp();
const accumulated = await TestContract.accumulated('1', wallet);
But I still get the error:
Error: sending a transaction requires a signer
(operation="sendTransaction", code=UNSUPPORTED_OPERATION,
version=contracts/5.5.0)
What am I missing?

Answer 1

You are trying to call a non-view function by using only a provider, you must provide a signer in order to call the function.
Try connecting to the contract using the wallet as the signer:
const TestContract = TestContract__factory.connect(getEnv('TEST_CONTRACT'), wallet);