Unit Tests in Truffle

In all the previous lessons, we tested our smart contracts manually, via Remix or by sending transactions using web3.js. Realistically, this could only work for simple smart contracts. If we're working on a complex project with other developers making changes, we need to automate the testing process.

The Truffle Framework allows implementing unit tests that can run a smart contract in a test environment, call methods on it, and validate the results. By adding unit tests to our contracts, we can ensure that our code is working correctly and catch bugs before the contract is deployed.

In this lesson, we'll start with writing tests for the Ownable smart contract, which is smaller and more straightforward. We'll keep tests for the Auction smart contract for a later lesson once we’ve learned the ropes.

Example of a test for a smart contract with Truffle

Truffle allows implementing tests in either JavaScript or Solidity, and since the former is more popular, we'll focus only on JavaScript in this course. To add a new test, we need to create an empty JavaScript file in a Truffle project’s test folder.

Let’s look at an example of a Truffle test file.