Minimal Solidity contract testing with Ganache and Jest

A Truffle project is a great way to start a dapp, but sometimes you want something more lightweight. For example, instead of having to pull-off migrations, maybe you just want to compile a simple smart contract and test right-away.

No worries, the Truffle suite of tools has got you covered! Using Ganache, you can easily spawn a test blockchain for your tests.

Note: This example uses solc to compile the contract. If you prefer to use truffle-contract (makes the JSON artifact a little easier to work with), check out the truffle-contract branch here.

Dependencies

In this example, there are only 4 dependencies!

• ganache-core — Allows us to spawn a "test blockchain".
• jest — A testing framework.
• solc — Compiles our Solidity contract.
• web3 — Allows us to interact with our contract and do other Ethereum things.

Files

There are only 3 files you need to be concerned about.

SimpleStorage.sol

This is a simple Solidity contract that we will use as our example. It allows you to set and get an integer and nothing more.

compile.js

This file houses a utility function that compiles Solidity contracts and spits out JSON we can work with. Do note that we only need two things from the JSON in this example:

1. The contract ABI, and;
2. The contract bytecode.

test.js

This file houses our tests. Notice that most of the heavy lifting is done in the beforeAll hook, where we:

• Compile the contract with solc;
• Spawn a "test blockchain" with ganache-core, and;
• Deploy our contract with web3.

In the afterAll hook, we simply call stop() on the Provider to clean up after ourselves.