如何使用Sinon处理嵌套函数？

function outerFunction() {
    return innerFunction();
}

function innerFunction() {
    return "Hello, World!";
}

const sinon = require('sinon');

describe('outerFunction', () => {
    let innerFunctionStub;

    beforeEach(() => {
        // 创建 innerFunction 的存根
        innerFunctionStub = sinon.stub(window, 'innerFunction');
    });

    afterEach(() => {
        // 恢复 innerFunction 的原始实现
        innerFunctionStub.restore();
    });

    it('should call innerFunction and return its result', () => {
        // 配置存根的返回值
        innerFunctionStub.returns("Mocked Result");

        const result = outerFunction();

        // 验证 innerFunction 是否被调用
        sinon.assert.calledOnce(innerFunctionStub);

        // 验证返回值
        expect(result).to.equal("Mocked Result");
    });
});