用 Jest 測試匿名函數的相等性

Question

有沒有辦法用jest@20測試匿名函數的相等性？

我正在嘗試通過類似於以下內容的測試：

const foo = i => j => {return i*j}
const bar = () => {baz:foo(2), boz:1}

describe('Test anonymous function equality',()=>{

    it('+++ foo', () => {
        const obj = foo(2)
        expect(obj).toBe(foo(2))
    });

    it('+++ bar', () => {
        const obj = bar()
        expect(obj).toEqual({baz:foo(2), boz:1})
    });    
});

目前產生：

  ● >>>Test anonymous function equality › +++ foo

    expect(received).toBe(expected)

    Expected value to be (using ===):
      [Function anonymous]
    Received:
      [Function anonymous]

    Difference:

    Compared values have no visual difference.

  ● >>>Test anonymous function equality › +++ bar

    expect(received).toBe(expected)

    Expected value to be (using ===):
      {baz: [Function anonymous], boz:1}
    Received:
      {baz: [Function anonymous], boz:1}

    Difference:

    Compared values have no visual difference.

Answer 1

在這種情況下，如果不重寫邏輯以使用命名函數，除了在 test 之前聲明函數之外，您真的沒有其他選擇，例如

const foo = i => j => i * j
const foo2 = foo(2)
const bar = () => ({ baz: foo2, boz: 1 })

describe('Test anonymous function equality', () => {
  it('+++ bar', () => {
    const obj = bar()
    expect(obj).toEqual({ baz: foo2, boz: 1 })
  });    
});

或者，您可以使用expect.any(Function)檢查obj.bar是否為any function ：

expect(obj).toEqual({ baz: expect.any(Function), boz: 1 })

根據測試的上下文，這實際上可能更有意義。