Flow Playground

Install Flow Javascript Testing Framework

How to install the Flow command-line interface (CLI)


If you have a non-JS project, you will need to initiate a project in your test folder first with:

npm init

Then install all necessary packages by running following command:

npm install flow-js-testing jest @babel/core @babel/preset-env babel-jest @onflow/types

If your project is JavaScript based, then run the above command from the folder that contains your project's package.json file.

Jest Config

You'll need to configure Jest in order for tests to work properly. Add jest.config.js file next to package.json and populate it with:

module.exports = {
  testEnvironment: "node",
  verbose: true,
  coveragePathIgnorePatterns: ["/node_modules/"],

Babel Config

Similarly, create babel.config.json then copy and paste the following configuration:

  "presets": [
        "targets": {
          "node": "current"