如何从另一个函数的输出对象模拟一个函数

Question

main.js

import { a } from './a.js';
const { output } = a();
const c = num => num + output.b();
export { c }

a.js

const a = () => ({
output: { b: () => 5 }, // I want to mock this function
});
export { a }

main.test.js

import { c } from './main.js';
describe('main file', () => {
test("c function", () => {
const result = c(4);
expect(result).toBe(9);
});
})

如何模拟output.b函数？

Answer 1

解决方案1

main.test.js:

import { c } from './main.js';
jest.mock('./a.js', () => ({
a: () => ({
output: { b: jest.fn(() => 15) }, // adding a mock function
}),
}));
describe('main file', () => {
test("c function", () => {
const result = c(4);
expect(result).toBe(19);
});
})

解决方案2

__mocks_/a.js:

const a = () => ({
output: { b: jest.fn(() => 15) },
});
export { a }

main.test.js:

import { c } from './main.js';
jest.mock('./a.js');
describe('main file', () => {
test("c function", () => {
const result = c(4);
expect(result).toBe(19);
});
})