Jest的`it.each()`描述用于在引用$谓词时呈现箭头函数源代码

问题定义

Jest允许在以下情况下使用测试用例的数据 it.each s name 通过 $ -前缀变量。

下面的代码会得到这样的输出:

 PASS  src/array-functions/find-pairwise.spec.ts
  findPairwise
    √ should return [1, 2] for [1, 2, 3] and [Function anonymous] (7ms)
    √ should return [1, 2] for [1, 2, 3] and [Function anonymous] (1ms)
    √ should return [2, 3] for [1, 2, 3] and [Function anonymous]
    √ should return [2, 3] for [1, 2, 3] and [Function anonymous] (1ms)
    √ should return [undefined, undefined] for [1, 2, 3] and [Function anonymous]

Test Suites: 1 passed, 1 total
Tests:       5 passed, 5 total
Snapshots:   0 total
Time:        4.061s
Ran all test suites related to changed files.

如您所见 $expected 和 $array 变量以人类友好的形式呈现(在这种情况下是基本的JavaScript数组)。 然而 $predicate 显示通用文本 [Function anonymous] 而不是实际的代码。 我知道JS中的常规函数和箭头函数都可以公开它们的源代码,如果你调用 .toString() 在他们身上。 有没有一种方法可以指示Jest渲染该结果 toString() 打电话? 我确实试过了 $predicate.toString() 和 $(predicate.toString()) 但它们都不起作用。

代码

import { findPairwise } from './find-pairwise';

describe(findPairwise.name, () => {
  it.each`
    array        | predicate                                | expected
    ${[1, 2, 3]} | ${(l: number, r: number) => l === 1}     | ${[1, 2]}
    ${[1, 2, 3]} | ${(l: number, r: number) => r === 2}     | ${[1, 2]}
    ${[1, 2, 3]} | ${(l: number, r: number) => r === 3}     | ${[2, 3]}
    ${[1, 2, 3]} | ${(l: number, r: number) => l + r === 5} | ${[2, 3]}
    ${[1, 2, 3]} | ${(l: number, r: number) => l === r }    | ${[undefined, undefined]}
  `
  ('should return $expected for $array and $predicate', ({ array, predicate, expected }) => {
//                                         ^^^^^^^^^^
//                                         ||||||||||
//                                         I'd like this to be rendered
//                                         as the code of the arrow function.
//                                         E.g. "(l: number, r: number) => l === 1"
//                                         ...or something close to it.

    expect(findPairwise(array, predicate)).toEqual(expected);
  });
});