我有一个新的background-repeat: no-repeat;
background-position: center center;
background-size: contain;
background-image: url(your/path/to.svg);
background-color: var(--color);
方法
Array.prototype如何编写测试用例以验证是否引发了错误？
// tslint:disable-next-line: interface-name
interface Array<T> {
random(): T;
randomInRange(): T;
}
Array.prototype.random = function random() {
if (this.length < 3) {
throw new Error();
}
return this[Math.floor(Math.random() * this.length)];
};
我也尝试过// prototypes.test.ts
import './prototypes';
describe('Test Array.prototype.random method', () => {
it('should return a random number from the array', () => {
const arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
const random = arr.random();
const isNumberPresentInArray = arr.includes(random);
expect(isNumberPresentInArray).toBe(true);
});
it('should throw error if there are less than 3 elements in the array', () => {
const arr = [1, 2];
expect(arr.random()).toThrow(new Error());
});
});
，但没有运气。