Jest encountered an unexpected token for Ag-Grid unit testing

Jest encountered an unexpected token for Ag-Grid unit testing

Unit testing is an essential part of software development, as it helps ensure the quality and reliability of our code. When working with TypeScript, Jest is a popular testing framework that provides a simple and effective way to write unit tests. However, when trying to test components that use Ag-Grid, you might encounter an unexpected token error. In this blog post, we will explore the possible solutions to this problem.

Solution 1: Configuring Jest to handle TypeScript files

The unexpected token error usually occurs when Jest encounters TypeScript files that it doesn’t know how to handle. To resolve this, we need to configure Jest to handle TypeScript files properly.

To configure Jest for TypeScript, you will need to install a few dependencies:

npm install --save-dev ts-jest @types/jest

Once the dependencies are installed, you can update your Jest configuration in the jest.config.js file:

module.exports = {
  transform: {
    '^.+\.tsx?$': 'ts-jest',
  },
};

This configuration tells Jest to use ts-jest as the transformer for TypeScript files. Now, when running your tests, Jest will be able to handle TypeScript files properly, and the unexpected token error should be resolved.

Solution 2: Mocking Ag-Grid dependencies

Another possible solution to the unexpected token error is to mock the Ag-Grid dependencies that are causing the problem. By mocking these dependencies, we can bypass the need for them during testing and avoid the unexpected token error.

To mock Ag-Grid dependencies, you can create a file called __mocks__/ag-grid.ts in your project’s root directory:

// __mocks__/ag-grid.ts
export const Grid = jest.fn();
export const ColDef = jest.fn();
export const GridOptions = jest.fn();

In this file, we are exporting mocked versions of the Ag-Grid dependencies that are causing the unexpected token error. Now, when running your tests, Jest will use these mocked versions instead of the actual Ag-Grid dependencies.

With these solutions in place, you should be able to overcome the unexpected token error when unit testing components that use Ag-Grid. Happy testing!

Final HTML Output:

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pre>

npm install --save-dev ts-jest @types/jest

module.exports = {
  transform: {
    '^.+\.tsx?$': 'ts-jest',
  },
};

// __mocks__/ag-grid.ts
export const Grid = jest.fn();
export const ColDef = jest.fn();
export const GridOptions = jest.fn();