expect `toBe` has misleading error message

Do you want to request a feature or report a bug? Feature (it is more like a fix)

What is the current behavior? Sometimes developer may want to check for identity. Currently, expect.toBe does this. But the error message is misleading:

Compared values have no visual difference. Looks like you wanted to test for object/array equality with strict `toBe` matcher. You probably need to use `toEqual` instead.

Because the message suggests to change toBe -> toEqual. So new developer may make this change which may lead to a bug in the project (or deoptimization).

I also think, that toBe and toEqual do not communicate the difference between each other clearly.

Suggestion

1. Maybe change name toBe -> toBeExact or toShallowEqual.
2. Maybe change message You probably need to use 'toEqual' instead. -> If you want to check for deep equality, pease, use 'toEqual' instead.
3. Maybe change toEqual -> toDeepEqual

[SimenB]

I like it

[ggarek]

Sure

file

test('identity check', () => {
  const value = {};
  const identity = x => Object.assign({}, x); // Wrong implementation
  expect(identity(value)).toBe(value);
});

output

  FAIL  src/test.js
  ● identity check

    expect(received).toBe(expected) // Object.is equality

    Expected value to be:
      {}
    Received:
      {}

    Difference:

    Compared values have no visual difference. Looks like you wanted to test for object/array equality with strict `toBe` matcher. You probably need to use `toEqual` instead.

      2 |   const value = {};
      3 |   const identity = x => Object.assign({}, x); // Wrong implementation
    > 4 |   expect(identity(value)).toBe(value);
      5 | });
      6 |

      at Object.<anonymous> (src/test.js:4:27)

jest v22.4.3