Jest - 外部化扩展期望匹配器

Question

我有。node.js-TypeScript 应用程序和 Jest 用于测试。使用此参考https://jestjs.io/docs/expect#expecttextendmatchers我的测试类中有一些扩展的期望匹配器。就像下面的例子一样。我在几个不同的测试类中有很多共同的扩展。有没有办法外部化/分组这些扩展匹配器并通过导入它们在测试类中使用？

例子：

expect.extend({
  async toBeDivisibleByExternalValue(received) {
    const externalValue = await getExternalValueFromRemoteSource();
    const pass = received % externalValue == 0;
    if (pass) {
      return {
        message: () =>
          `expected ${received} not to be divisible by ${externalValue}`,
        pass: true,
      };
    } else {
      return {
        message: () =>
          `expected ${received} to be divisible by ${externalValue}`,
        pass: false,
      };
    }
  },
});

test('is divisible by external value', async () => {
  await expect(100).toBeDivisibleByExternalValue();
  await expect(101).not.toBeDivisibleByExternalValue();
});

我的笑话.d.ts:

export {};
declare global {
  namespace jest {
    interface Matchers<R> {
      hasTestData(): R;
    }
}

Answer 1

对于常见的扩展期望，我使用以下逻辑；

扩展期望.ts：

declare global {
    namespace jest {
        interface Matchers<R> {
            toBeDivisibleByExternalValue(): R;
        }
    }
}
export function toBeDivisibleByExternalValue(received:any): jest.CustomMatcherResult {
    const externalValue = await getExternalValueFromRemoteSource();
    const pass = received % externalValue == 0;
    if (pass) {
      return {
        message: () =>
          `expected ${received} not to be divisible by ${externalValue}`,
        pass: true,
      };
    } else {
      return {
        message: () =>
          `expected ${received} to be divisible by ${externalValue}`,
        pass: false,
      };
    }
}

定义了常用方法，现在如何使用它；

你的测试类看起来像，

import { toBeDivisibleByExternalValue } from "../ExtendedExpects";

expect.extend({
   toBeDivisibleByExternalValue
});

test('is divisible by external value', async () => {
  await expect(100).toBeDivisibleByExternalValue();
  await expect(101).not.toBeDivisibleByExternalValue();
});

您不再需要 jest.d.ts。