如何断言数组包含 JavaScript/TYPEScript 中的子字符串

Question

我正在尝试检查数组中是否存在 SubString。在测试中我断言使用：

expect(classList).toContain('Rail__focused')

我收到以下错误：

Error: expect(received).toContain(expected // indexOf
Expected value: "Rail__focused"
Received array: ["Rail__item__3NvGX", "Rail__focused__3bGTR", "Tile__tile__3jJYQ", "Tile__wide__1GuVb", "Tile__animated__3H87p", "Tile__active__1mtVd"]

这就是我想要实现的目标并希望它通过

var arr = ["Rail__item__3NvGX", "Rail__focused__3bGTR", "Tile__tile__3jJYQ", "Tile__wide__1GuVb", "Tile__animated__3H87p", "Tile__active__1mtVd"];
 
var str =  'Rail__focused';
for (var i = 0, len = arr.length; i < len; ++i) {
    if (str.indexOf(arr[i]) != -1) {
        console.log("This is a pass")
    } else {
    console.log("This is a fail")
    }
}

Answer 1

所以因为屏幕截图中有一个 Jest d.ts - 我只是假设这是 Jest :)

.contain does a strict === 检查 - 所以这不适用于部分字符串。

例如，您可以在数组中搜索项目并断言它存在：

test('contain', () => {
  const classList = [
    'Rail__item__3NvGX',
    'Rail__focused__3bGTR',
    'Tile__tile__3jJYQ',
    'Tile__wide__1GuVb',
    'Tile__animated__3H87p',
    'Tile__active__1mtVd',
  ];
  expect(classList.find((el) => el.includes('Rail__focused'))).toBeDefined();
});

Array.find 会返回第一个满足回调结果的元素。它将返回 undefined - 如果没有找到。

如果这是一个重复的任务 - 你可以写一个custom matcher in Jest：

expect.extend({
  toPartiallyContain(received, needle) {
    const pass = received.find((el) => el.includes(needle));
    if (pass) {
      return {
        message: () =>
          `expected ${received} not to partially contain ${needle}`,
        pass: true,
      };
    } else {
      return {
        message: () => `expected ${received} to partially contain ${needle}`,
        pass: false,
      };
    }
  },
});

test('contain with custom matcher', () => {
  const classList = [
    'Rail__item__3NvGX',
    'Rail__focused__3bGTR',
    'Tile__tile__3jJYQ',
    'Tile__wide__1GuVb',
    'Tile__animated__3H87p',
    'Tile__active__1mtVd',
  ];
  expect(classList).toPartiallyContain('Rail__focused');
  expect(classList).not.toPartiallyContain('Hello');
});

您的示例没有测试断言：

var arr = ["Rail__item__3NvGX", "Rail__focused__3bGTR", "Tile__tile__3jJYQ", "Tile__wide__1GuVb", "Tile__animated__3H87p", "Tile__active__1mtVd"];
 
var str =  'Rail__focused';

console.log(arr.find((el) => el.includes(str)));