Jest testing guide

This library doesn't require any mocks. However unit tests are running in Node.js runtime and dynamic import statement doesn't work out-of-box. To make your tests running again you'll need to add dynamic-import-node plugin for test environment and modify your babel.config.js or .babelrc files accordingly.

Installing new babel dependency

First of all you'll need to install babel-plugin-dynamic-import-node to devDependencies.

yarn add babel-plugin-dynamic-import-node --dev
# or
# npm install babel-plugin-dynamic-import-node --save-dev

Add plugin to babel config

If you are using babel.config.js format, then you can add conditional statement to include dynamic-import-node plugin only for test environment.

// The plugin was added because jest can't use dynamic imports and was changing the imports and
// final module had following shape { __esModule: true, default: RealModule }.
// So, react-native-bundle-splitter can't resolve this import format.
if (process.env.NODE_ENV === "test") {
  config.plugins.push("dynamic-import-node");
}

If you are using JSON format (i. e. .babelrc), then you'll need to add plugin under env.test key.

{
    "presets": ...
    "plugins": [
        ...
    ],
    "env": {
        "test": {
            "plugins": ["dynamic-import-node"]
        }
    }
}