Implemented the `.toMatchObject(object)` assertion #1843

excitement-engineer · 2016-10-02T16:54:58Z

Summary

Implemented the toMatchObject(object) function that checks whether an object matches a subset of the properties of another object. This was discussed in issue #1793.

This matcher works for objects with a combination of key/value pairs, arrays and javascript dates:

const input1 = {a: 'b', t: {z: 'z', x: {r: 'r'}}};
const matcher1 = {a: 'b', t: {z: 'z'}};

const input2 = {a: new Date('2015-11-30'), b: 'b'};
const matcher2 =  {a: new Date('2015-11-30')};

const input3 = {a: [3, 4, 5], b: 'b'};
const matcher3 =  {a: [3, 4]};

//these tests pass now
expect(input1).toMatchObject(matcher1);
expect(input2).toMatchObject(matcher2);
expect(input3).toMatchObject(matcher3);

facebook-github-bot · 2016-10-02T16:55:47Z

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codecov-io · 2016-10-02T17:09:43Z

Current coverage is 88.95% (diff: 98.27%)

Merging #1843 into master will increase coverage by 0.38%

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+ Hits           1248       1305    +57   
- Misses          161        162     +1   
  Partials          0          0

Powered by Codecov. Last update 4e9e4df...5becc2e

facebook-github-bot · 2016-10-02T17:28:38Z

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quantizor · 2016-10-04T04:12:32Z

Can this be the default for .toHaveBeenCalledWith when comparing objects, @cpojer?

cpojer · 2016-10-04T04:13:48Z

No, I would prefer toBeCalledWith etc. to stay strict.

excitement-engineer · 2016-11-05T18:23:19Z

Any updates on the status of this PR?

cpojer · 2016-11-07T09:42:09Z

@excitement-engineer would you mind rebasing this diff?

excitement-engineer · 2016-11-08T20:42:58Z

@cpojer I have performed the rebase:)

cpojer · 2016-11-08T20:44:11Z

Ok thanks! @DmitriiAbramov is going to handle this whenever he gets around to it :)

excitement-engineer · 2016-11-08T20:46:37Z

Great! Thanks a lot for your help!

aaronabramov · 2016-11-16T05:15:07Z

packages/jest-matchers/src/__tests__/matchers-test.js

+    [{a: 'b', t: {z: 'z', x: {r: 'r'}}}, {a: 'b', t: {z: 'z'}}],
+    [{a: 'b', t: {z: 'z', x: {r: 'r'}}}, {t: {x: {r: 'r'}}}],
+    [{a: [3, 4, 5], b: 'b'}, {a: [3, 4, 5]}],
+    [{a: [3, 4, 5], b: 'b'}, {a: [3, 4]}],


i'm a little scared to have the same behavior on arrays.
Properties definitely make sense, but for arrays it can be dangerous if you match some enums or other sets.

for example, this will pass, and it's pretty straightforward:

expect({permissions: ['read', 'write'], ...manyOtherProps}).toMathcObject({permissions: ['read']});

but if the left side is a return of the function, that might be not intuitive and even confusing:

expect(getPermissions()).toMathcObject({permissions: ['read']}); // i expect it to be just 'read', but there's and extra value that i don't even see, and the test is passing

should we match only objects, and use strict equality for arrays? what do you think?

I agree with you! I have removed this behaviour and have added a check that an equality check is performed for the elements in the array.

So this test will now fail:

expect({permissions: ['read', 'write'], ...manyOtherProps}).toMatchObject({permissions: ['read']});

There is one exception with the equality check mentioned above; you can still perform matchObject checks for key-value objects contained in arrays (i.e. array of objects), so in my update this will pass:

expect([{a: 'a', b: 'b'}, 5]).toMatchObject([{a: 'a'}, 5])

Do you agree with this behaviour?

aaronabramov · 2016-11-16T05:24:59Z

packages/jest-matchers/src/matchers.js

+    if (typeof receivedObject !== 'object' || receivedObject === null) {
+      throw new Error(
+        matcherHint('[.not].toMatch', 'object', 'expected') + '\n\n' +
+        `${RECEIVED_COLOR('string')} value must be an object.\n` +


right now it prints

you probably copied 'string' from .toMatch matcher :)

i'm trying to think of a good message.

Expect object to be an object. Received

or

Expect expected to be an object. Received:

look king of weird.

maybe something like:

<red>object</red> value must be an object. Received:

and

<green>expected</green> value must be an object. Received:

thoughts?

Whoops, thanks for catching that, haha a bit embarrassing that I didn't see this;)

I implemented your suggestion:

<green>expected</green> value must be an object. Received:

aaronabramov · 2016-11-16T05:52:57Z

packages/jest-matchers/src/matchers.js

+    const message = pass
+      ? () => matcherHint('.not.toMatchObject') +
+     `\n\nExpected value not to match object:\n` +
+     `  ${printExpected(JSON.stringify(expectedObject))}` +


we can't really use JSON.stringify here.
you should use printExpected and printReceived, they won't break on circular references and will handle other special values like undefined and friends :)

i think what we should also print is a diff between the entire expected and filtered received object, with only properties that matter. something like:

expect({a: 1, b: 1, c: 1, d: {e: {f: 555}}}).toMatch({d: {e: {f: 222}}}); Expected object to match: {d: {e: {f: 222}}} Received: {a: 1, b: 1, c: 1, d: {e: {f: 555}}} Difference: { d: { e: { + f: 555, - f: 222 } } }

Thanks for the tip, I have changed the code!

Any tips on how I can implement this diffing? Is it an idea to update the jest-diff package with a new DiffOption?

I think I have an idea. I will delete all the properties that are contained in the Received object but not contained in the matching object. I can then just use jest-diff without introducing any changes there! Expect an update with this soon!

# Conflicts: # packages/jest-matchers/src/__tests__/matchers-test.js

excitement-engineer · 2016-11-24T07:58:05Z

@DmitriiAbramov I have made all the changes that you suggested in your code review. Let me know what you think!

aaronabramov · 2016-11-28T18:24:46Z

this PR is awesome! thank you so much @excitement-engineer!
and sorry for the long response. holiday season in the US :)

excitement-engineer · 2016-11-28T18:27:26Z

Thanks a lot for you help! No worries about the timing:)

chodorowicz · 2016-12-13T09:24:37Z

Guys, just to let you know: toMatchObject documentation is already official and live but the code is not present in the most recent release v17.0.3 so we're getting TypeError: expect(...).toMatchObject is not a function.

https://facebook.github.io/jest/docs/api.html#tomatchobjectobject
https://github.com/facebook/jest/blob/v17.0.3/packages/jest-matchers/src/matchers.js#L479

thymikee · 2016-12-13T09:28:11Z

Yea, this was already reported in #2195 :D Thanks!

* Implemented .toMatchObject() * Fixed error message and array equality in toMatchObject() * Fixed listing errors. * toMatchObject now displays a diff when a test fails

github-actions · 2021-05-14T04:10:09Z

This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.
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facebook-github-bot added the CLA Signed ✔️ label Oct 2, 2016

facebook-github-bot added the CLA Signed ✔️ label Oct 4, 2016

cpojer assigned aaronabramov Nov 7, 2016

Implemented .toMatchObject()

47cbd9c

aaronabramov suggested changes Nov 16, 2016

View reviewed changes

jwbay mentioned this pull request Nov 20, 2016

Partial matching for mock assertions #2137

Closed

excitement-engineer added 4 commits November 20, 2016 16:48

Fixed error message and array equality in toMatchObject()

1caa765

Fixed listing errors.

e83cbe9

Merge remote-tracking branch 'facebook/master'

f5991b6

# Conflicts: # packages/jest-matchers/src/__tests__/matchers-test.js

toMatchObject now displays a diff when a test fails

5becc2e

aaronabramov merged commit 8188ab9 into jestjs:master Nov 28, 2016

pedrottimark mentioned this pull request Dec 2, 2016

New shape matcher proposal #2202

Closed

ismay mentioned this pull request Jan 5, 2017

Match object recursively (toMatchObject) #2506

Closed

github-actions bot locked as resolved and limited conversation to collaborators May 14, 2021

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Implemented the `.toMatchObject(object)` assertion #1843

Implemented the `.toMatchObject(object)` assertion #1843

excitement-engineer commented Oct 2, 2016

facebook-github-bot commented Oct 2, 2016

codecov-io commented Oct 2, 2016 •

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quantizor commented Oct 4, 2016

cpojer commented Oct 4, 2016

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cpojer commented Nov 7, 2016

excitement-engineer commented Nov 8, 2016

cpojer commented Nov 8, 2016

excitement-engineer commented Nov 8, 2016

aaronabramov Nov 16, 2016

excitement-engineer Nov 20, 2016

aaronabramov Nov 16, 2016

excitement-engineer Nov 20, 2016

aaronabramov Nov 16, 2016

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excitement-engineer Nov 20, 2016

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excitement-engineer commented Nov 28, 2016

chodorowicz commented Dec 13, 2016 •

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thymikee commented Dec 13, 2016

github-actions bot commented May 14, 2021

Implemented the .toMatchObject(object) assertion #1843

Implemented the .toMatchObject(object) assertion #1843

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excitement-engineer commented Oct 2, 2016

facebook-github-bot commented Oct 2, 2016

codecov-io commented Oct 2, 2016 • edited Loading

Current coverage is 88.95% (diff: 98.27%)

facebook-github-bot commented Oct 2, 2016

quantizor commented Oct 4, 2016

cpojer commented Oct 4, 2016

excitement-engineer commented Nov 5, 2016

cpojer commented Nov 7, 2016

excitement-engineer commented Nov 8, 2016

cpojer commented Nov 8, 2016

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excitement-engineer commented Nov 24, 2016

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chodorowicz commented Dec 13, 2016 • edited Loading

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github-actions bot commented May 14, 2021

Implemented the `.toMatchObject(object)` assertion #1843

Implemented the `.toMatchObject(object)` assertion #1843

codecov-io commented Oct 2, 2016 •

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