Jest Mock Module Example

jest-mock-eg.js

// Path to the module to mock
// Then function which is called when the module is accessed
jest.mock("../mocked-module", () => ({
  // Allows for multiple exports and a default to be mocked out individually
  __esModule: true,
  // Immediately returning the args like this is a substitute for inspecting the calledWith 
  // on a mock (Jest mock does not allow access to surrounding variables like a closure would)
  default: jest.fn(args => args),
  API_METHOD: { POST: "POST" }
}));

// More simple example just returns a named export from a module
jest.mock('../mocked-module', () => ({
  upsert: (payload: TSType) => payload.changed
}))

// Even simpler example just gets around an imported module causing an error outside the unit
// you're testing
jest.mock('../mocked-module', jest.fn())