toEqual doesn't verify key value of type undefined

[erikologic]

#9763 🐛 Bug Report

When verifying an object, if a key is set to undefined it will not be verified.

To Reproduce

it('pass', () => {
    expect({
        key: true
    }).toEqual({
        key: true,
        anotherKey: undefined
    });
});

it('pass too', () => {
    expect({
        key: true,
        anotherKey: undefined
    }).toEqual({
        key: true
    });
});

Expected behavior

IMO it should fail because key anotherKey is not existing in the other object, regardless for it being set to undefined.

Link to repl or repo (highly encouraged)

NA

envinfo

  System:
    OS: macOS 10.15.4
    CPU: (8) x64 Intel(R) Core(TM) i5-8257U CPU @ 1.40GHz
  Binaries:
    Node: 12.16.0 - ~/.nvm/versions/node/v12.16.0/bin/node
    Yarn: 1.22.4 - ~/.nvm/versions/node/v12.16.0/bin/yarn
    npm: 6.14.5 - ~/.nvm/versions/node/v12.16.0/bin/npm
  npmPackages:
    jest: ^26.0.1 => 26.0.1 

[SimenB]

You should use toStrictEqual for this. Does it need specification in docs?

[erikologic]

Sorry I missed it totally... :(

Does it need specification in docs?

Do you mean in the .toEqual section?
Maybe that would help

[github-actions]

This issue is stale because it has been open for 1 year with no activity. Remove stale label or comment or this will be closed in 30 days.

[github-actions]

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