jest-automock

This package allows you to automock the methods on a class instance. Mostly useful when using dependency injection, but can come in useful when mocking the return of a factory too.

Usage

Import using:

import { autoMock } from 'jest-automock';

Create a mock using:

let mockClass = autoMock(ClassConstructor);

This will replace all of the instance methods on the class provided with jest mocks, allowing you to check that those methods have been called, as well as mocking what they should return.

If using TypeScript, the autoMock function returns a jest.Mocked<T> type, with T being the class that you passed in. This allows you to access all of the class methods, as well as the mocking methods that appear on a mocked function.

For a more detailed example, see below:

## Example

import { autoMock } from 'jest-automock';

/* Class that will be mocked */
class HttpClient {
  get(url) {
    // Real implementation here
  }
}

/* Consumer of mocked class - class that we are testing */
class TodoHttpService {
  constructor(private httpClient: HttpClient) {}

  public getAllTodos() {
    return this.httpClient.get('api-url/todos');
  }
}

/* Test suite */
describe('TodoHttpService', () => {
  let service: TodoHttpService, mockHttpClient: jest.Mocked<HttpClient>;

  beforeEach(() => {
    mockHttpClient = autoMock(HttpClient);
    mockHttpClient.get.mockReturnValue('todos');
    service = new TodoHttpService(mockHttpClient);
  });

  describe('getAllTodos', () => {
    let result;

    beforeEach(() => {
      result = service.getAllTodos();
    });

    it('should fetch the todos', () => {
      expect(mockHttpClient.get).toHaveBeenCalledWith('api-url/todos');
    });

    it('should return the todos', () => {
      expect(result).toBe('todos');
    });
  });
});