@jest/globals

Defining tests

Allows the definition of test cases. The `test` function is used to define a block of code that tests a specific part of your application. The `expect` function is used to make an assertion about a particular value.

import { test, expect } from '@jest/globals';

test('adds 1 + 2 to equal 3', () => {
  expect(1 + 2).toBe(3);
});

Mocking functions

Enables the mocking of functions, allowing you to simulate the behavior of your code's dependencies. This is useful for isolating the code under test and controlling its environment.

import { jest } from '@jest/globals';

const mockFn = jest.fn();
mockFn.mockReturnValue('mocked value');

expect(mockFn()).toBe('mocked value');

Grouping tests

Provides a way to group related tests using the `describe` function. This helps in organizing tests, especially when testing complex applications.

import { describe, test, expect } from '@jest/globals';

describe('math operations', () => {
  test('adds 1 + 2 to equal 3', () => {
    expect(1 + 2).toBe(3);
  });

  test('subtracts 2 - 1 to equal 1', () => {
    expect(2 - 1).toBe(1);
  });
});