# Is there a way to test on a local blockchain with OpenZeppelin Test Environment? **URL:** \ **Category:** Support\ **Created:** [November 12, 2020, 6:43pm UTC](https://forum.openzeppelin.com/t/is-there-a-way-to-test-on-a-local-blockchain-with-openzeppelin-test-environment/4564 "2020-11-12T18:43:29Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![minhdinh1](https://avatars.discourse-cdn.com/v4/letter/m/c77e96/32.png) [@minhdinh1](https://forum.openzeppelin.com/u/minhdinh1)\ **Post date:** [November 12, 2020, 6:43pm UTC](https://forum.openzeppelin.com/t/is-there-a-way-to-test-on-a-local-blockchain-with-openzeppelin-test-environment/4564/1 "2020-11-12T18:43:29Z")
Hi, I’m wondering if there’s a way to automate test for testnet in a similar way to testing on a local blockchain with test-environment and test-helpers? ---
**Author:** ![abcoathup](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.openzeppelin.com/abcoathup/32/415_2.png) [@abcoathup](https://forum.openzeppelin.com/u/abcoathup)\ **Post date:** [November 13, 2020, 5:09am UTC](https://forum.openzeppelin.com/t/is-there-a-way-to-test-on-a-local-blockchain-with-openzeppelin-test-environment/4564/2 "2020-11-13T05:09:55Z")
Hi @minhdinh1, With OpenZeppelin Test Environment you can fork an existing blockchain (such as mainnet or a public testnet) and run your tests against that network. See the documentation for details on configuring fork: [https://docs.openzeppelin.com/test-environment/0.1/getting-started#fork\_and\_unlocked\_accounts](https://docs.openzeppelin.com/test-environment/0.1/getting-started#fork_and_unlocked_accounts) ---
**Author:** ![minhdinh1](https://avatars.discourse-cdn.com/v4/letter/m/c77e96/32.png) [@minhdinh1](https://forum.openzeppelin.com/u/minhdinh1)\ **Post date:** [November 13, 2020, 9:26pm UTC](https://forum.openzeppelin.com/t/is-there-a-way-to-test-on-a-local-blockchain-with-openzeppelin-test-environment/4564/3 "2020-11-13T21:26:06Z")
In order to fork an existing blockchain, do I need to deploy my contract up to the testnet first and use the block number after? And what does unlocked-accounts mean in the documentation you mentioned. Sorry, I’m still new to smart contract testing ---
**Author:** ![abcoathup](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.openzeppelin.com/abcoathup/32/415_2.png) [@abcoathup](https://forum.openzeppelin.com/u/abcoathup)\ **Post date:** [November 15, 2020, 9:40pm UTC](https://forum.openzeppelin.com/t/is-there-a-way-to-test-on-a-local-blockchain-with-openzeppelin-test-environment/4564/4 "2020-11-15T21:40:07Z")
Hi @minhdinh1, Your tests will deploy your contracts to the local fork of the blockchain. `unlocked_accounts` is an array of accounts that you want to unlock so that you can send transactions from these accounts. ---
**Author:** ![minhdinh1](https://avatars.discourse-cdn.com/v4/letter/m/c77e96/32.png) [@minhdinh1](https://forum.openzeppelin.com/u/minhdinh1)\ **Post date:** [November 17, 2020, 10:53pm UTC](https://forum.openzeppelin.com/t/is-there-a-way-to-test-on-a-local-blockchain-with-openzeppelin-test-environment/4564/5 "2020-11-17T22:53:01Z")
Hi, I’ve tried changing the test environment config in test-environment.config.js to fork from rinkeby testnet but it all of the test just fail at the setup token stage with this error. 1) LuniverseGluwacoin\_Initialization “before each” hook for “token name is LuniverseGluwacoin”: Uncaught Error: Unhandled server error at Object.default\_1 [as default] (node\_modules/@openzeppelin/test-environment/src/setup-ganache.ts:69:15) at processTicksAndRejections (internal/process/task\_queues.js:97:5) at /mnt/c/Work/WSL\_files/Luniverse-Gluwacoin/node\_modules/@openzeppelin/test-environment/src/test-provider.ts:20:19 at run (node\_modules/p-queue/dist/index.js:163:29) Is there any more steps that I need to take to successfully run my test code on rinkeby testnet the same way it ran on the local blockchain? My node packages version are: npm 6.14.6 truffle v5.1.49 mocha 8.2.0 test-helper 0.5.7 test-environment 0.1.5 ---
**Author:** ![abcoathup](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.openzeppelin.com/abcoathup/32/415_2.png) [@abcoathup](https://forum.openzeppelin.com/u/abcoathup)\ **Post date:** [November 18, 2020, 7:12am UTC](https://forum.openzeppelin.com/t/is-there-a-way-to-test-on-a-local-blockchain-with-openzeppelin-test-environment/4564/6 "2020-11-18T07:12:07Z")
Hi @minhdinh1, If your tests run locally then you just need to change your `test-environment.config.js` to include what you want to fork. As per: [https://docs.openzeppelin.com/test-environment/0.1/getting-started#fork\_and\_unlocked\_accounts](https://docs.openzeppelin.com/test-environment/0.1/getting-started#fork_and_unlocked_accounts) I used Infura, but you could use Alchemy or another provider, see: [https://docs.openzeppelin.com/learn/connecting-to-public-test-networks#accessing-a-testnet-node](https://docs.openzeppelin.com/learn/connecting-to-public-test-networks#accessing-a-testnet-node). Testing against a fork takes time, so I recommend increasing the timeout. Please find below a simple example I used: ## test-environment.config.js ```auto // test-environment.config.js const { infuraProjectId, } = require('./secrets.json'); module.exports = { node: { // Options passed directly to Ganache client fork: `https://rinkeby.infura.io/v3/${infuraProjectId}`, // An url to Ethereum node to use as a source for a fork }, }; ``` ## secrets.json I keep my Infura Project ID (or other API key secret) in `secrets.json` but you could use any secret keeping approach (❗ don’t commit any secrets to version control) ```auto { "infuraProjectId": "MY INFURA PROJECT ID" } ``` ## package.json Testing against a fork is slow, so recommend increasing the timeout when running `mocha`. ```auto { ... "scripts": { "test": "mocha --exit --recursive --timeout 10000" }, ... } ``` ## Box.sol From: [https://docs.openzeppelin.com/learn/developing-smart-contracts#first-contract](https://docs.openzeppelin.com/learn/developing-smart-contracts#first-contract) ```auto // contracts/Box.sol // SPDX-License-Identifier: MIT pragma solidity ^0.6.0; contract Box { uint256 private value; // Emitted when the stored value changes event ValueChanged(uint256 newValue); // Stores a new value in the contract function store(uint256 newValue) public { value = newValue; emit ValueChanged(newValue); } // Reads the last stored value function retrieve() public view returns (uint256) { return value; } } ``` ## Box.test.js From: [https://docs.openzeppelin.com/learn/writing-automated-tests#test-environment](https://docs.openzeppelin.com/learn/writing-automated-tests#test-environment) ```auto // test/Box.test.js // Load dependencies const { accounts, contract } = require('@openzeppelin/test-environment'); const { expect } = require('chai'); // Load compiled artifacts const Box = contract.fromArtifact('Box'); // Start test block describe('Box', function () { const [owner] = accounts; beforeEach(async function () { // Deploy a new Box contract for each test this.contract = await Box.new({ from: owner }); }); // Test case it('retrieve returns a value previously stored', async function () { // Store a value - recall that only the owner account can do this! await this.contract.store(42, { from: owner }); // Test if the returned value is the same one // Note that we need to use strings to compare the 256 bit integers expect((await this.contract.retrieve()).toString()).to.equal('42'); }); }); ``` ## Test ```auto $ npm run test > minhdinh1@1.0.0 test /home/abcoathup/projects/forum/minhdinh1 > mocha --exit --recursive --timeout 10000 Box ✓ retrieve returns a value previously stored (397ms) 1 passing (5s) ``` ---
**Author:** ![minhdinh1](https://avatars.discourse-cdn.com/v4/letter/m/c77e96/32.png) [@minhdinh1](https://forum.openzeppelin.com/u/minhdinh1)\ **Post date:** [November 18, 2020, 10:00pm UTC](https://forum.openzeppelin.com/t/is-there-a-way-to-test-on-a-local-blockchain-with-openzeppelin-test-environment/4564/7 "2020-11-18T22:00:06Z")
Thanks, I’m able to run my local tests on the testnet now. I think the reason why my tests failed before is because settings that are caused through migrations and manually deploying and running contract functions to test on the testnet. I manage to run my test on testnet by resetting the project to the point before I manually do the things I mentioned above. ---
**Author:** ![abcoathup](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.openzeppelin.com/abcoathup/32/415_2.png) [@abcoathup](https://forum.openzeppelin.com/u/abcoathup)\ **Post date:** [November 18, 2020, 10:08pm UTC](https://forum.openzeppelin.com/t/is-there-a-way-to-test-on-a-local-blockchain-with-openzeppelin-test-environment/4564/8 "2020-11-18T22:08:14Z")
Hi @minhdinh1, Glad to hear that you are up and running with your tests. You could deploy any contracts that you need in a `before` or `beforeEach` in your tests.