Jest transformIgnorePatterns not working

Question

I have spent a long time looking at other questions about this and looking at other projects on Github but none of the answers seem to work for me.

I am loading a third party library in my project, and when running Jest tests I get the error

export default portalCommunication;
^^^^^^

SyntaxError: Unexpected token export

> 1 | import portalCommunication from 'mathletics-portal-communication-service';

I have tried updating my Jest config in many ways to get it to transpile this library but I always get the same error.

This is my current jest.config.js file:

module.exports = {
    moduleNameMapper: {
        '\\.(css|scss)$': 'identity-obj-proxy',
        '\\.svg$': '<rootDir>/test/mocks/svg-mock.js'
    },
    setupFiles: ['./test/test-setup.js'],
    transformIgnorePatterns: [
        '<rootDir>/node_modules/(?!mathletics-portal-communication-service)'
    ]
};

I have also tried adding the transform property to run babel-jest against this mathletics-portal-communication-service directory.

Please help!

Answer 1

The transformIgnorePatterns didn't work for me until I changed my .babelrc to babel.config.js, like this:

module.exports = {
    "presets": [
        "@babel/preset-env"
    ]
};

as seen on this comment: https://github.com/facebook/jest/issues/6229#issuecomment-403539460

Answer 2

As a workaround for now I have changed my config to use the moduleNameMapper option to load a mock class for that library instead. I would have preferred to use transformIgnorePatterns instead so would still appreciate any ideas.

New config:

module.exports = {
    moduleNameMapper: {
        '\\.(css|scss)$': 'identity-obj-proxy',
        '\\.svg$': '<rootDir>/test/mocks/svg-mock.js',
        'mathletics-portal-communication-service': '<rootDir>/test/mocks/mathletics-portal-communication-service-mock.js'
    },
    setupFiles: ['./test/test-setup.js']
};

Answer 3

Adding trailing slash fix this for me:

{
    // ...
    transformIgnorePatterns: [
        '<rootDir>/node_modules/(?!mathletics-portal-communication-service/)'
    ]
};