jest mock implementation
describe("mockImplementation", () => {
test("function", () => {
const mockFn1 = jest.fn().mockImplementation(() => 42);
const mockFn2 = jest.fn(() => 42);
expect(mockFn1()).toBe(42);
expect(mockFn2()).toBe(42);
});jest mock method by name
import Foo from './Foo';
import Bar from './Bar';
jest.mock('./Bar');
describe('Foo', () => {
it('should return correct foo', () => {
// As Bar is already mocked,
// we just need to cast it to jest.Mock (for TypeScript) and mock whatever you want
(Bar.prototype.runBar as jest.Mock).mockReturnValue('Mocked bar');
const foo = new Foo();
expect(foo.runFoo()).toBe('real foo : Mocked bar');
});
});jest mock mockname
test("mockName", () => {
const mockFn = jest.fn().mockName("mockedFunction");
mockFn(); // comment me
expect(mockFn).toHaveBeenCalled();
});Copyright © 2021 Codeinu
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