sinon-stub-framework

import { stub } from 'sinon-stub-framework'; class MyService { fetchData(id) { return Promise.resolve(`Data for ${id}`); } processData(data) { return data.toUpperCase(); } } describe('MyService', () => { let myService; let fetchDataStub; beforeEach(() => { myService = new MyService(); // Stub a method to control its behavior during tests fetchDataStub = stub(myService, 'fetchData'); }); afterEach(() => { // Restore the original method after each test fetchDataStub.restore(); }); it('should return stubbed data', async () => { fetchDataStub.returns(Promise.resolve('Mocked Data')); const result = await myService.fetchData(1); expect(result).toBe('Mocked Data'); expect(fetchDataStub.calledOnceWith(1)).toBe(true); }); it('should throw an error when stubbed', async () => { const errorMessage = 'Network Error!'; fetchDataStub.throws(new Error(errorMessage)); await expect(myService.fetchData(2)).rejects.toThrow(errorMessage); expect(fetchDataStub.calledOnceWith(2)).toBe(true); }); it('should process data correctly even with stubbed dependency', () => { fetchDataStub.returns(Promise.resolve('raw data')); // Test another method that might rely on fetchData but we control its output const processed = myService.processData('another data'); // Assuming processData doesn't call fetchData here for simplicity expect(processed).toBe('ANOTHER DATA'); }); });