How to Write Tests with Chukti

This guide will walk you through writing tests for a Solidity contract using Chukti.

1. Writing a Solidity Contract

Let's start by writing a simple Solidity contract named Counter.sol. Place this contract inside contracts/ directory of your Chukti project.

contracts/counter.sol

// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.13;

contract Counter {
    uint256 private number;

    constructor(uint256 _number) {
        number = _number;
    }

    function getNumber() public view returns (uint256) {
        return number;
    }

    function setNumber(uint256 _number) public {
        number = _number;
    }

    function increment() public {
        number++;
    }

    function decrement() public {
        number--;
    }

    function resetNumber() public {
        number = 0;
    }

    function incrementBy(uint256 _value) public {
        number += _value;
    }
}

2. Creating a Feature Test File

Next, we will create a feature test file named counter.feature to test the Counter contract. This file will be located in the features/ directory.

features/counter.feature

Feature: Counter contract example

  Scenario: Deploy and interact with the Counter contract
    Given I have a smart contract located at "contracts/Counter.sol"
    When I deploy the smart contract with constructor arguments "[10]" and send "0" Ether
    Then I validate the deployment status is "success"

    When I call the read function "getNumber" from the contract with arguments "[]"
    Then I store the result in "currentNumber"
    And I validate the value stored in "currentNumber" should be "equal to" "10"

    When I call the write function "increment" from the contract with arguments "[]" and send "0" Ether
    Then I validate the status of the last transaction is "success"

    And I call the read function "getNumber" from the contract with arguments "[]"
    Then I store the result in "currentNumber"
    And I validate the value stored in "currentNumber" should be "equal to" "11"

3. Running the test

To run the test, follow these steps:

1. Open your terminal and navigate to the Chukti project's root directory
2. Run the Chukti test command:

npm

npx chukti test

pnpm

pnpm dlx chukti test

if Chukti installed globally

chukti test

This command will execute the feature test file and generate a test report. You can check the test report in the test-reports folder.

4. Explanation

Let's break down what the feature test file is doing step by step:

• Check Contract Existence and Compile:

  • The first step verifies that the Counter.sol contract exists at the specified path (contracts/Counter.sol).
  • It also checks the compiled artifacts exist of that contract or not.

• Deploy the Contract:

  • The contract is deployed with the constructor argument [10], which sets the initial value of number to 10.
  • As no Ether was required for this contract's deployment, the amount sent is 0.

• Read the Initial Value:

  • The getNumber function is called to read the current value of number.
  • The result is stored in the variable currentNumber.
  • The test checks that currentNumber is equal to 10, confirming that the contract was deployed correctly with the initial value.

• Increment the Value:

  • The increment function is called to increase the value of number by 1.
  • The test confirms that the transaction was successful.

• Read the Incremented Value:

  • The getNumber function is called again to read the updated value of number.
  • The result is stored in the variable currentNumber.
  • The test checks that currentNumber is equal to 11, confirming that the increment function worked as expected.

By following these steps, the feature test file ensures that the Counter contract is correctly deployed, and its increment function behaves as expected.