nested objectContaining does not show diff

🐛 Bug Report

Using expect.objectContaining in nested in another objectContaining will not trigger a diff.

To Reproduce

expect({ data: [{ a: 1 }, { a: 2 }] }).toEqual(
      expect.objectContaining({
        data: [
          expect.objectContaining({ a: 2 }),
          expect.objectContaining({ a: 2 }),
        ],
      })
    );

expect({ a: 1, b: { c: 'c' }, c: 'd' }).toEqual(expect.objectContaining({
      a: 3,
      b: expect.objectContaining({ c: 'd' }),
      c: expect.stringMatching('c'),
    }));

Expected behavior

I would expect to see a diff showing why the objects are different. Note that this already happens when we use just one level of objectContaining inside an array (see tests: objectContaining within array and 'objectContaining in array)

Link to repl or repo (highly encouraged)

https://repl.it/repls/CooperativeRipeBruteforceprogramming#nested.test.js

envinfo

  System:
    OS: macOS 10.15.5
    CPU: (8) x64 Intel(R) Core(TM) i7-1068NG7 CPU @ 2.30GHz
  Binaries:
    Node: 14.4.0 - /usr/local/bin/node
    npm: 6.14.5 - /usr/local/bin/npm
  npmPackages:
    jest: ^26.1.0 => 26.1.0

[SamLee]

I believe this is only the case when you pass an asymmetric matcher function into toEqual. When passing an object that has nested objectContainings within it, I receive a diff output.

Looking at the source jest-matcher-utils contains a function isLineDiffable and if the expected or actual object is an asymmetric matcher function it returns false

[vteivans]

@SamLee is there another way to write it? toMatchObject requires all object properties to be defined if an object is an outer level.

If I use expect(someArr).toCountainEqual(expect.objectContaining({...})), I still don’t get the diff either.