How to write code coverage for error block in mocha chai?

@lizzie 

In order to write code coverage for error blocks in Mocha Chai, you can follow these steps:

1. Install a code coverage tool like Istanbul or NYC. You can install it using npm:

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npm install --save-dev nyc

1. Add a script in your package.json file to run the code coverage tool. For example:

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"scripts": {
  "test": "mocha --recursive tests && nyc report --reporter=text-summary"
}

1. Write your test cases in Mocha Chai that cover the error block in your code. For example:

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const expect = require('chai').expect;

describe('Error handling', () => {
  it('should throw an error when the input is invalid', () => {
    expect(() => {
      // Call the function with invalid input
      throw new Error('Invalid input');
    }).to.throw('Invalid input');
  });
});

1. Run your test script to generate code coverage reports:

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npm test

1. Check the generated code coverage report to see the coverage of your error block.

By following these steps, you can write code coverage for error blocks in Mocha Chai and ensure that your error handling code is thoroughly tested.