toMatchObject throws TypeError when a source property is null

[massimonewsuk]

test.only("foo", () => {
  expect({ foo: null }).toMatchObject({ foo: { bar: "baz" } });
});

This code gives a TypeError as opposed to a nice assertion error.

Both myself and my colleague have had this issue this week and both of us took about an hour to realise it was a problem with Jest and not our code.

[thymikee]

Please conform to issue template and provide a repro and detailed error message.

[SimenB]

This is pretty bad...

Repro: https://repl.it/repls/PersonalVisibleCustomer
Error message:

Should be easy enough to fix though, mind sending a PR?

[massimonewsuk]

@SimenB thanks for posting the shot etc

We're over-capacity at the moment so unfortunately unable to submit any PRs, but if things cool down and nobody's fixed it then I don't mind picking it up, thanks!

[SimenB]

The stack trace before asynchronicity blows it away (on current master):

    TypeError: Cannot convert undefined or null to object
        at hasOwnProperty (<anonymous>)
        at Object.<anonymous>.exports.hasOwnProperty (/Users/simbekkh/repos/jest/packages/expect/build/utils.js:12:35)
        at Object.keys.every.key (/Users/simbekkh/repos/jest/packages/expect/build/utils.js:222:7)
        at Array.every (<anonymous>)
        at Array.Object.<anonymous>.exports.subsetEquality (/Users/simbekkh/repos/jest/packages/expect/build/utils.js:220:30)
        at eq (/Users/simbekkh/repos/jest/packages/expect/build/jasmine_utils.js:77:46)
        at equals (/Users/simbekkh/repos/jest/packages/expect/build/jasmine_utils.js:17:10)
        at Object.keys.every.key (/Users/simbekkh/repos/jest/packages/expect/build/utils.js:223:33)
        at Array.every (<anonymous>)
        at Array.Object.<anonymous>.exports.subsetEquality (/Users/simbekkh/repos/jest/packages/expect/build/utils.js:220:30)

[thymikee]

Closed via #6313, will be up in next patch release

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