Testing Anonymous Equality Function with Jest

Question

Is there a way to check the anonymous equality of a function with jest@20?

I am trying to pass a test similar to:

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})
    });    
});

which currently gives:

  ● >>>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

In such a situation, without rewriting your logic for using named functions, you really have no choice but to declare the function before the test , for example

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 })
  });    
});

Alternatively, you can verify that obj.bar any function using expect.any(Function):

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

which may make sense depending on the context of the test.