Testing Setup

Because of deep integration with libauth, CashScript allows for local transaction evaluation without actual interaction with any Bitcoin Cash test network. With a MockNetwork environment you can create virtual UTXOs without doing additional preparations. This has the advantages of not needing any testnet balances, not having to set up smart contract UTXOs and not having network latency. This setup allows for using a testing framework to run repeated automated tests for increased smart contract security.

For a quick start with a CashScript testing setup, you can check out our testing-suite example that demonstrates a full development and testing environment for CashScript contracts, similar to Hardhat on Ethereum.

caution

The CashScript debugging tools only work with the Simple Transaction Builder. We plan to extend the debugging tools to work with the Advanced Transaction Builder in the future.

MockNetworkProvider

The MockNetworkProvider is a special network provider that allows you to evaluate transactions locally without interacting with the Bitcoin Cash network. This is useful when writing automated tests for your contracts, or when debugging your contract locally. By default, it generates some random mock UTXOs for the contract address, but you can also add your own UTXOs to the provider.

import { MockNetworkProvider, randomUtxo, randomToken, randomNFT } from 'cashscript';

const provider = new MockNetworkProvider();
provider.addUtxo(contract.address, { vout: 0, txid: "ab...", satoshis: 10000n });

provider.addUtxo(aliceAddress, randomUtxo({
  satoshis: 1000n,
  token: { ...randomNFT(), ...randomToken() },
}));

note

The MockNetworkProvider only evaluates the transactions locally, so any UTXOs added to a transaction still count as "unspent", even after mocking a sendTransaction using the provider.

Automated testing

To make writing automated tests for CashScript contracts easier, we provide a Jest extension that enables easy testing of console.log values and require error messages. To use the extension, you can import it from cashscript/jest.

import 'cashscript/jest';

note

If you're using a different testing framework, you can test for console.log values by spying on the console output, and test for require error messages by asserting that an error is thrown with a specific error message.

With local transaction evaluation and debugging, it is possible to write efficient automated tests for CashScript contracts to test specific contract behaviour and check console.log values and require error messages.

Logging values

You can log values during debug evaluation using the console.log statement. Any variables or primitive values (such as ints, strings, bytes, ...) can be logged.

note

Logging is only available in debug evaluation of a transaction. It has no impact on the compiled bytecode or regular (non-debug) execution.

describe('Example contract', () => {
  it('should log the passed parameter', async () => {
    const contract = new Contract(artifact, [], { provider });
    const transaction = contract.functions.exampleFunction(1000n).to(contract.address, 10000n);
    await expect(transaction).toLog('passed parameter: 1000');
  });
});

Error messages

The require statement accepts an optional error message as a second argument. If the condition in the require statement is not met during debug evaluation, the error message is returned. This allows you to write automated tests that check for specific error messages.

note

Similar to console.log, the error message in a require statement is only available in debug evaluation of a transaction, so the error message has no impact on the compiled bytecode or regular (non-debug) execution.

describe('Example contract', () => {
  const contract = new Contract(artifact, [], { provider });

  it('should fail require statement when incorrect parameter is passed', async () => {
    const transaction = contract.functions.exampleFunction(999n).to(contract.address, 10000n);
    await expect(transaction).toFailRequireWith('passed parameter is not 1000');
  });

  it('should pass require statement when correct parameter is passed', async () => {
    const transaction = contract.functions.exampleFunction(1000n).to(contract.address, 10000n);
    await expect(transaction).not.toFailRequire();
  });
});

Full Example

Example contract

contract Example() {
  function exampleFunction(int value) {
    console.log("passed parameter:", value);
    require(value == 1000, "passed parameter is not 1000");
  }
}

Example test file

import artifact from '../artifacts/example.json' with { type: "json" };
import { Contract, MockNetworkProvider, randomUtxo } from 'cashscript';
import 'cashscript/jest';

describe('Example contract', () => {
  const contract = new Contract(artifact, [], { provider });
  const provider = new MockNetworkProvider();
  provider.addUtxo(contract.address, randomUtxo());

  it('should log the passed parameter', async () => {
    const contract = new Contract(artifact, [], { provider });
    const transaction = contract.functions.exampleFunction(1000n).to(contract.address, 10000n);
    await expect(transaction).toLog('passed parameter: 1000');
  });

  it('should fail require statement when incorrect parameter is passed', async () => {
    const transaction = contract.functions.exampleFunction(999n).to(contract.address, 10000n);
    await expect(transaction).toFailRequireWith('passed parameter is not 1000');
  });

  it('should pass require statement when correct parameter is passed', async () => {
    const transaction = contract.functions.exampleFunction(1000n).to(contract.address, 10000n);
    await expect(transaction).not.toFailRequire();
  });
});