wp-calypso/test/packages/jest.config.js

module.exports = {
	rootDir: './../../',
	// run tests for all packages that have a Jest config file
	projects: [ '<rootDir>/packages/*/jest.config.js' ],
	moduleNameMapper: {
		'react-markdown': '<rootDir>/node_modules/react-markdown/react-markdown.min.js',
	},
};