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Fix handling circular references correctly in objects (closes #8663) #8687

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1 change: 1 addition & 0 deletions CHANGELOG.md
Expand Up @@ -24,6 +24,7 @@
- `[jest-core]` Fix incorrect `passWithNoTests` warning ([#8595](https://github.com/facebook/jest/pull/8595))
- `[jest-snapshots]` Fix test retries that contain snapshots ([#8629](https://github.com/facebook/jest/pull/8629))
- `[jest-mock]` Fix incorrect assignments when restoring mocks in instances where they originally didn't exist ([#8631](https://github.com/facebook/jest/pull/8631))
- `[expect]` Fix stack overflow when matching objects with circular references ([#8687](https://github.com/facebook/jest/pull/8687))

### Chore & Maintenance

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98 changes: 98 additions & 0 deletions packages/expect/src/__tests__/__snapshots__/matchers.test.js.snap
Expand Up @@ -4092,6 +4092,104 @@ Expected: not <green>Set {2, 1}</>
Received: <red>Set {1, 2}</>"
`;

exports[`toMatchObject() circular references simple circular references {pass: false} expect({"a": "hello", "ref": [Circular]}).toMatchObject({"a": "world", "ref": [Circular]}) 1`] = `"Maximum call stack size exceeded"`;

exports[`toMatchObject() circular references simple circular references {pass: false} expect({"ref": "not a ref"}).toMatchObject({"a": "hello", "ref": [Circular]}) 1`] = `
"<dim>expect(</><red>received</><dim>).</>toMatchObject<dim>(</><green>expected</><dim>)</>

<green>- Expected</>
<red>+ Received</>

<dim> Object {</>
<green>- \\"a\\": \\"hello\\",</>
<green>- \\"ref\\": [Circular],</>
<red>+ \\"ref\\": \\"not a ref\\",</>
<dim> }</>"
`;

exports[`toMatchObject() circular references simple circular references {pass: false} expect({}).toMatchObject({"a": "hello", "ref": [Circular]}) 1`] = `
"<dim>expect(</><red>received</><dim>).</>toMatchObject<dim>(</><green>expected</><dim>)</>

<green>- Expected</>
<red>+ Received</>

<green>- Object {</>
<green>- \\"a\\": \\"hello\\",</>
<green>- \\"ref\\": [Circular],</>
<green>- }</>
<red>+ Object {}</>"
`;

exports[`toMatchObject() circular references simple circular references {pass: true} expect({"a": "hello", "ref": [Circular]}).toMatchObject({"a": "hello", "ref": [Circular]}) 1`] = `
"<dim>expect(</><red>received</><dim>).</>not<dim>.</>toMatchObject<dim>(</><green>expected</><dim>)</>

Expected: not <green>{\\"a\\": \\"hello\\", \\"ref\\": [Circular]}</>"
`;

exports[`toMatchObject() circular references simple circular references {pass: true} expect({"a": "hello", "ref": [Circular]}).toMatchObject({}) 1`] = `
"<dim>expect(</><red>received</><dim>).</>not<dim>.</>toMatchObject<dim>(</><green>expected</><dim>)</>

Expected: not <green>{}</>
Received: <red>{\\"a\\": \\"hello\\", \\"ref\\": [Circular]}</>"
`;

exports[`toMatchObject() circular references transitive circular references {pass: false} expect({"a": "world", "nestedObj": {"parentObj": [Circular]}}).toMatchObject({"a": "hello", "nestedObj": {"parentObj": [Circular]}}) 1`] = `"Maximum call stack size exceeded"`;
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@lucasfcosta I have added some line breaks so you can verify if the long-line snapshot is the intended criterion:

exports[
`toMatchObject() circular references simple circular references {pass: false}
expect({"a": "hello", "ref": [Circular]})
.toMatchObject({"a": "world", "ref": [Circular]}) 1`
] =
`"Maximum call stack size exceeded"`;

I think it is from test case: [circularObjA1, circularObjB]

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Excellent catch! I have just fixed that. Please see the Appendix below.

Thank you @pedrottimark


exports[`toMatchObject() circular references transitive circular references {pass: false} expect({"nestedObj": {"parentObj": "not the parent ref"}}).toMatchObject({"a": "hello", "nestedObj": {"parentObj": [Circular]}}) 1`] = `
"<dim>expect(</><red>received</><dim>).</>toMatchObject<dim>(</><green>expected</><dim>)</>

<green>- Expected</>
<red>+ Received</>

<dim> Object {</>
<green>- \\"a\\": \\"hello\\",</>
<dim> \\"nestedObj\\": Object {</>
<green>- \\"parentObj\\": [Circular],</>
<red>+ \\"parentObj\\": \\"not the parent ref\\",</>
<dim> },</>
<dim> }</>"
`;

exports[`toMatchObject() circular references transitive circular references {pass: false} expect({}).toMatchObject({"a": "hello", "nestedObj": {"parentObj": [Circular]}}) 1`] = `
"<dim>expect(</><red>received</><dim>).</>toMatchObject<dim>(</><green>expected</><dim>)</>

<green>- Expected</>
<red>+ Received</>

<green>- Object {</>
<green>- \\"a\\": \\"hello\\",</>
<green>- \\"nestedObj\\": Object {</>
<green>- \\"parentObj\\": [Circular],</>
<green>- },</>
<green>- }</>
<red>+ Object {}</>"
`;

exports[`toMatchObject() circular references transitive circular references {pass: true} expect({"a": "hello", "nestedObj": {"parentObj": [Circular]}}).toMatchObject({"a": "hello", "nestedObj": {"parentObj": [Circular]}}) 1`] = `
"<dim>expect(</><red>received</><dim>).</>not<dim>.</>toMatchObject<dim>(</><green>expected</><dim>)</>

Expected: not <green>{\\"a\\": \\"hello\\", \\"nestedObj\\": {\\"parentObj\\": [Circular]}}</>"
`;

exports[`toMatchObject() circular references transitive circular references {pass: true} expect({"a": "hello", "nestedObj": {"parentObj": [Circular]}}).toMatchObject({}) 1`] = `
"<dim>expect(</><red>received</><dim>).</>not<dim>.</>toMatchObject<dim>(</><green>expected</><dim>)</>

Expected: not <green>{}</>
Received: <red>{\\"a\\": \\"hello\\", \\"nestedObj\\": {\\"parentObj\\": [Circular]}}</>"
`;

exports[`toMatchObject() does not match properties up in the prototype chain 1`] = `
"<dim>expect(</><red>received</><dim>).</>toMatchObject<dim>(</><green>expected</><dim>)</>

<green>- Expected</>
<red>+ Received</>

<dim> Object {</>
<dim> \\"other\\": \\"child\\",</>
<green>- \\"ref\\": [Circular],</>
<dim> }</>"
`;

exports[`toMatchObject() throws expect("44").toMatchObject({}) 1`] = `
"<dim>expect(</><red>received</><dim>).</>toMatchObject<dim>(</><green>expected</><dim>)</>

Expand Down
126 changes: 104 additions & 22 deletions packages/expect/src/__tests__/matchers.test.js
Expand Up @@ -1537,7 +1537,91 @@ describe('toMatchObject()', () => {
}
}

[
const testNotToMatchSnapshots = tuples => {
tuples.forEach(([n1, n2]) => {
it(`{pass: true} expect(${stringify(n1)}).toMatchObject(${stringify(
n2,
)})`, () => {
jestExpect(n1).toMatchObject(n2);
expect(() =>
jestExpect(n1).not.toMatchObject(n2),
).toThrowErrorMatchingSnapshot();
});
});
};

const testToMatchSnapshots = tuples => {
tuples.forEach(([n1, n2]) => {
it(`{pass: false} expect(${stringify(n1)}).toMatchObject(${stringify(
n2,
)})`, () => {
jestExpect(n1).not.toMatchObject(n2);
expect(() =>
jestExpect(n1).toMatchObject(n2),
).toThrowErrorMatchingSnapshot();
});
});
};

describe('circular references', () => {
describe('simple circular references', () => {
const circularObjA1 = {a: 'hello'};
circularObjA1.ref = circularObjA1;

const circularObjB = {a: 'world'};
circularObjB.ref = circularObjB;

const circularObjA2 = {a: 'hello'};
circularObjA2.ref = circularObjA2;

const primitiveInsteadOfRef = {};
primitiveInsteadOfRef.ref = 'not a ref';

testNotToMatchSnapshots([
[circularObjA1, {}],
[circularObjA2, circularObjA1],
]);

testToMatchSnapshots([
[{}, circularObjA1],
[circularObjA1, circularObjB],
[primitiveInsteadOfRef, circularObjA1],
]);
});

describe('transitive circular references', () => {
const transitiveCircularObjA1 = {a: 'hello'};
transitiveCircularObjA1.nestedObj = {parentObj: transitiveCircularObjA1};

const transitiveCircularObjA2 = {a: 'hello'};
transitiveCircularObjA2.nestedObj = {
parentObj: transitiveCircularObjA2,
};

const transitiveCircularObjB = {a: 'world'};
transitiveCircularObjB.nestedObj = {
parentObj: transitiveCircularObjB,
};

const primitiveInsteadOfRef = {};
primitiveInsteadOfRef.nestedObj = {
parentObj: 'not the parent ref',
};

testNotToMatchSnapshots([
[transitiveCircularObjA1, {}],
[transitiveCircularObjA2, transitiveCircularObjA1],
]);

testToMatchSnapshots([
[{}, transitiveCircularObjA1],
[transitiveCircularObjB, transitiveCircularObjA1],
[primitiveInsteadOfRef, transitiveCircularObjA1],
]);
});
});

testNotToMatchSnapshots([
[{a: 'b', c: 'd'}, {a: 'b'}],
[{a: 'b', c: 'd'}, {a: 'b', c: 'd'}],
[{a: 'b', t: {x: {r: 'r'}, z: 'z'}}, {a: 'b', t: {z: 'z'}}],
Expand All @@ -1560,18 +1644,9 @@ describe('toMatchObject()', () => {
[new Error('bar'), {message: 'bar'}],
[new Foo(), {a: undefined, b: 'b'}],
[Object.assign(Object.create(null), {a: 'b'}), {a: 'b'}],
].forEach(([n1, n2]) => {
it(`{pass: true} expect(${stringify(n1)}).toMatchObject(${stringify(
n2,
)})`, () => {
jestExpect(n1).toMatchObject(n2);
expect(() =>
jestExpect(n1).not.toMatchObject(n2),
).toThrowErrorMatchingSnapshot();
});
});
]);

[
testToMatchSnapshots([
[{a: 'b', c: 'd'}, {e: 'b'}],
[{a: 'b', c: 'd'}, {a: 'b!', c: 'd'}],
[{a: 'a', c: 'd'}, {a: jestExpect.any(Number)}],
Expand All @@ -1597,16 +1672,7 @@ describe('toMatchObject()', () => {
[[1, 2, 3], [1, 2, 2]],
[new Error('foo'), new Error('bar')],
[Object.assign(Object.create(null), {a: 'b'}), {c: 'd'}],
].forEach(([n1, n2]) => {
it(`{pass: false} expect(${stringify(n1)}).toMatchObject(${stringify(
n2,
)})`, () => {
jestExpect(n1).not.toMatchObject(n2);
expect(() =>
jestExpect(n1).toMatchObject(n2),
).toThrowErrorMatchingSnapshot();
});
});
]);

[
[null, {}],
Expand All @@ -1628,4 +1694,20 @@ describe('toMatchObject()', () => {
).toThrowErrorMatchingSnapshot();
});
});

it('does not match properties up in the prototype chain', () => {
const a = {};
a.ref = a;

const b = Object.create(a);
b.other = 'child';

const matcher = {other: 'child'};
matcher.ref = matcher;

jestExpect(b).not.toMatchObject(matcher);
expect(() =>
jestExpect(b).toMatchObject(matcher),
).toThrowErrorMatchingSnapshot();
});
});
54 changes: 54 additions & 0 deletions packages/expect/src/__tests__/utils.test.js
Expand Up @@ -202,6 +202,60 @@ describe('subsetEquality()', () => {
test('undefined does not return errors', () => {
expect(subsetEquality(undefined, {foo: 'bar'})).not.toBeTruthy();
});

describe('matching subsets with circular references', () => {
test('simple circular references', () => {
const circularObjA1 = {a: 'hello'};
circularObjA1.ref = circularObjA1;

const circularObjA2 = {a: 'hello'};
circularObjA2.ref = circularObjA2;

const circularObjB = {a: 'world'};
circularObjB.ref = circularObjB;

const primitiveInsteadOfRef = {};
primitiveInsteadOfRef.ref = 'not a ref';

expect(subsetEquality(circularObjA1, {})).toBe(true);
expect(subsetEquality({}, circularObjA1)).toBe(false);
expect(subsetEquality(circularObjA2, circularObjA1)).toBe(true);
expect(subsetEquality(circularObjB, circularObjA1)).toBe(false);
expect(subsetEquality(primitiveInsteadOfRef, circularObjA1)).toBe(false);
});

test('transitive circular references', () => {
const transitiveCircularObjA1 = {a: 'hello'};
transitiveCircularObjA1.nestedObj = {parentObj: transitiveCircularObjA1};

const transitiveCircularObjA2 = {a: 'hello'};
transitiveCircularObjA2.nestedObj = {
parentObj: transitiveCircularObjA2,
};

const transitiveCircularObjB = {a: 'world'};
transitiveCircularObjB.nestedObj = {
parentObj: transitiveCircularObjB,
};

const primitiveInsteadOfRef = {};
primitiveInsteadOfRef.nestedObj = {
parentObj: 'not the parent ref',
};

expect(subsetEquality(transitiveCircularObjA1, {})).toBe(true);
expect(subsetEquality({}, transitiveCircularObjA1)).toBe(false);
expect(
subsetEquality(transitiveCircularObjA2, transitiveCircularObjA1),
).toBe(true);
expect(
subsetEquality(transitiveCircularObjB, transitiveCircularObjA1),
).toBe(false);
expect(
subsetEquality(primitiveInsteadOfRef, transitiveCircularObjA1),
).toBe(false);
});
});
});

describe('iterableEquality', () => {
Expand Down
38 changes: 29 additions & 9 deletions packages/expect/src/utils.ts
Expand Up @@ -268,16 +268,36 @@ export const subsetEquality = (
object: any,
subset: any,
): undefined | boolean => {
if (!isObjectWithKeys(subset)) {
return undefined;
}
// subsetEquality needs to keep track of the references
// it has already visited to avoid infinite loops in case
// there are circular references in the subset passed to it.
const subsetEqualityWithContext = (
seenReferences: WeakMap<object, boolean> = new WeakMap(),
) => (object: any, subset: any): undefined | boolean => {
if (!isObjectWithKeys(subset)) {
return undefined;
}

return Object.keys(subset).every(
key =>
object != null &&
hasOwnProperty(object, key) &&
equals(object[key], subset[key], [iterableEquality, subsetEquality]),
);
return Object.keys(subset).every(key => {
if (isObjectWithKeys(subset[key])) {
if (seenReferences.get(subset[key])) {
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return equals(object[key], subset[key], [iterableEquality]);
}
seenReferences.set(subset[key], true);
}

return (
object != null &&
hasOwnProperty(object, key) &&
equals(object[key], subset[key], [
iterableEquality,
subsetEqualityWithContext(seenReferences),
])
);
});
};

return subsetEqualityWithContext()(object, subset);
};

export const typeEquality = (a: any, b: any) => {
Expand Down