Testing throw with Jest

Revati S Misra 1001 20 Jul 2023

1 Answers

Aryan Kumar 20 Jul 2023

Sure, here are the steps on how to test throw with Jest:

First, you need to install Jest if you don't have it already. You can do this by running the following command in your terminal:

npm install -g jest

Once Jest is installed, you need to create a Jest configuration file. This file will tell Jest where to find your unit tests and how to run them. You can create a Jest configuration file by running the following command in your terminal:

jest --init

This will create a file called jest.config.js in your current directory. You can open this file and edit it to specify the location of your unit tests. For example, if your unit tests are located in a folder called tests, you would add the following line to your jest.config.js file:

"testPathIgnorePatterns": ["node_modules"]

Once you have created your Jest configuration file, you can start writing your unit tests. To test for a throw, you can use the expect.toThrow matcher. For example, the following unit test will test whether the function myFunction throws an error:

test("myFunction throws an error", () => {
  expect(myFunction()).toThrow();
});

Once you have written your unit tests, you can run them by running the following command in your terminal:

jest

This will run all of your unit tests and report any failures.

Here are some additional tips for testing throw with Jest:

You can use the expect.toThrowError matcher to test for a specific type of error. For example, the following unit test will test whether the function myFunction throws a TypeError error:

test("myFunction throws a TypeError", () => {
  expect(myFunction()).toThrowError(TypeError);
});

You can use the expect.toThrowWith matcher to test for a specific error message. For example, the following unit test will test whether the function myFunction throws an error with the message "This is an error message":

test("myFunction throws an error with the message 'This is an error message'", () => {
  expect(myFunction()).toThrowWith(TypeError, "This is an error message");
});

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Testing throw with Jest

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