How to Fix SyntaxError: Cannot use import statement outside a module in Jest

Learn how to resolve the common Jest error "SyntaxError: Cannot use import statement outside a module" when using TypeScript and Babel.
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How to Fix SyntaxError: Cannot use import statement outside a module in Jest

When working with Jest, TypeScript, and Babel, encountering the error SyntaxError: Cannot use import statement outside a module can be a common stumbling block. This error generally pops up when Jest tries to run tests that include ES6 module import statements. This guide offers some practical steps to resolve this issue.

Understanding the Problem

To successfully use ES6 import/export syntax in your tests, the test runner (Jest in this case) needs to be correctly configured to understand these statements. Jest by default does not understand ES6 modules, which leads to this particular error.

Resolution Steps

Install Necessary Dependencies

Firstly, ensure you have all the necessary dependencies installed. You will need:

@babel/preset-env

@babel/preset-typescript

babel-jest

jest

typescript

You can install them using npm or yarn:

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or

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Configure Babel

Create a .babelrc file to configure Babel to handle TypeScript and ES6 modules:

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This configuration tells Babel to transpile code using the environment preset and TypeScript preset.

Set Up Jest Configuration

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This configuration tells Jest to use babel-jest and ts-jest to transform your files based on their extensions. It makes sure that both JavaScript (including ES6) and TypeScript files are correctly handled.

Testing the Setup

Once you have updated your dependencies and configuration files, run your Jest tests using:

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or

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Doing so should resolve the SyntaxError: Cannot use import statement outside a module issue and allow your Jest tests to execute correctly.

Conclusion

By correctly configuring Babel and Jest, you can seamlessly use ES6 import/export statements in your tests without encountering syntax errors. Ensuring all the necessary dependencies are properly installed and configured is key to overcoming this common hurdle when working with modern JavaScript and TypeScript.