spyOn 即使通过函数也不会被调用

Question

我为 ngOnChanges 创建了一个测试，但即使它通过了函数，有一个错误

Error: Expected spy selectItem to have been called.

这是我的 ngOnChange

ngOnChanges(changes: SimpleChanges): void {
        const eventDataChange: SimpleChange = changes['selectEventData'];

        if (eventDataChange) {
            this.selectItem(eventDataChange.currentValue);
        }
    }

这是单元测试：

describe('ngOnChange()', () => {
        it('this is a description', () => {
            const selectDto = 'test';
            const eventDataChange: SimpleChange = new SimpleChange(null, selectDto, false);
            const simpleChanges: SimpleChanges = {
                selectEventData: eventDataChange
            };

            component.ngOnChanges(simpleChanges);

            const selectSpy = spyOn(component, 'selectItem');

            expect(selectSpy).toHaveBeenCalled();
        });
    });

希望得到善意的回应！

谢谢！

Answer 1

spyOn 间谍只会在间谍注册后调用。在您的示例中， spyOn() 在调用 ngOnChanges() 之后执行，这就是问题所在。只需将 spyOn() 调用移到 ngOnChanges() 调用之前：

const selectSpy = spyOn(component, 'selectItem');
component.ngOnChanges(simpleChanges);
expect(selectSpy).toHaveBeenCalled();

spyOn 即使通过函数也不会被调用

spyOn is not called even though it passed through the function

jasmine

karma-runner

angular