cw-simulate

This package combines cosmwasm-vm-js with additional abstractions and state management to more accurately simulate the effects of CosmWasm contracts on the blockchain environments on which they are hosted.

Features

• configure multiple host chain environments with chain-specific settings / state
• multiple simultaneous contract instances can exist per chain
• chain modules can be simulated through custom user code
• extensible for further instrumentation via custom middlewares

Getting Started

Import the cw-simulate library from NPM in your package.json.

$ npm install -S @terran-one/cw-simulate

If you're using Yarn:

$ yarn add @terran-one/cw-simulate

Usage

1. Create a CWSimulateApp object - this is a simulation environment describing a single chain.
2. As needed, per chain:
   • Upload the WASM bytecode using App.wasm.create. This will register a new codeId to reference the uploaded contract code.
   • Create a new contract instance using App.wasm.instantiateContract, passing in the codeId generated in the previous step.
   • From the response, retrieve the contractAddress to refer to the contract instance.

• You can now run execute and query messages against the instance, and they should work as expected.

Example

The following example creates a chain, instantiates a contract on it, and performs an execute and query.

import { CWSimulateApp } from '@terran-one/cw-simulate';
import { readFileSync } from 'fs';

const sender = 'terra1hgm0p7khfk85zpz5v0j8wnej3a90w709vhkdfu';
const funds = [];
const wasmBytecode = readFileSync('cw-template.wasm');

const app = new CWSimulateApp({
  chainId: 'phoenix-1',
  bech32Prefix: 'terra'
});

// import the wasm bytecode
const codeId = app.wasm.create(sender, wasmBytecode);

// instantiate the contract
let result = await app.wasm.instantiateContract(sender, funds, codeId, { count: 0 });
console.log('instantiateContract:', result.constructor.name, JSON.stringify(result, null, 2));

// pull out the contract address
const contractAddress = result.val.events[0].attributes[0].value;

// execute the contract
result = await app.wasm.executeContract(sender, funds, contractAddress, { increment: {} });
console.log('executeContract:', result.constructor.name, JSON.stringify(result, null, 2));

// query the contract
result = await app.wasm.query(contractAddress, { get_count: {} });
console.log('query:', result.constructor.name, JSON.stringify(result, null, 2));

Using with Vue.js and vite

Vite doesn't include shims for Node variables like Webpack 4 does, and cw-simulate currently relies on these. The following workaround exists:

1. Add the buffer package (npm add buffer)
2. Add the following to your index.html (inside the body tag, before your other js imports):

<script>
  window.global = window;
</script>
<script type="module">
  import {Buffer} from "buffer";
  window.Buffer = Buffer;
</script>

See this github issue for more details.