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fix: Strict equality for errors and throws custom classes #13607

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fix: Strict equality for errors and throws custom classes #13607

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57d94b2
fix: Strict equality for errors and throws custom classes
lpizzinidev Nov 12, 2022
d7ab1bd
Merge branch 'main' into fix-13604
SimenB Dec 31, 2022
f108b95
changelog
SimenB Dec 31, 2022
a567bb4
use jestexpect
SimenB Dec 31, 2022
df9fd4d
Merge branch 'main' into fix-13604
SimenB Dec 31, 2022
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1 change: 1 addition & 0 deletions CHANGELOG.md
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Expand Up @@ -6,6 +6,7 @@

### Fixes

- `[expect, @jest/expect-utils]` `toThrow` should handle custom `Error` classes ([#13607](https://github.com/facebook/jest/pull/13607))
- `[@jest/expect-utils]` `toMatchObject` should handle `Symbol` properties ([#13639](https://github.com/facebook/jest/pull/13639))
- `[jest-resolve]` Add global paths to `require.resolve.paths` ([#13633](https://github.com/facebook/jest/pull/13633))

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4 changes: 3 additions & 1 deletion packages/expect-utils/src/jasmineUtils.ts
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Expand Up @@ -83,7 +83,9 @@ function eq(
}

if (a instanceof Error && b instanceof Error) {
return a.message == b.message;
// Compare just error messages only if not strict check
if (!strictCheck) return a.message == b.message;
if (a.message != b.message) return false;
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this seems somewhat odd to me - should we stop comparing Errors unless their message matches? Is the thought that we want to treat that as any other objects?

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With the previous implementation, the discriminant determining Errors equality was only the message field.
With this implementation, you compare only the messages for non-strict equality, and you treat the two objects as any other object for strict equality checks.

It probably depends on how you think strict equality should be intended for Error objects.

}

if (Object.is(a, b)) {
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39 changes: 39 additions & 0 deletions packages/expect/src/__tests__/matchers.test.js
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Expand Up @@ -2334,3 +2334,42 @@ describe('toMatchObject()', () => {
});
});
});

describe('Error match', () => {
// Issue 13604
class CustomError extends Error {
constructor(message, otherField) {
super(message);
this.otherField = otherField;
}
}

class CustomObject {
constructor(someField) {
this.someField = someField;
}
}

it('custom error strict equality', () => {
jestExpect(new CustomError('message1', 'value1')).toStrictEqual(
new CustomError('message1', 'value1'),
);
jestExpect(new CustomError('message1', 'value1')).not.toStrictEqual(
new CustomError('message2', 'value1'),
);
jestExpect(new CustomError('message1', 'value1')).not.toStrictEqual(
new CustomError('message2', 'value2'),
);
jestExpect(new CustomError('message1', 'value1')).not.toStrictEqual(
new CustomError('message1', 'value2'),
);
});

it('throw custom object not extending Error', () => {
const fn = () => {
throw new CustomObject('value');
};

jestExpect(fn).toThrow(new CustomObject('value'));
});
});
6 changes: 4 additions & 2 deletions packages/expect/src/toThrowMatchers.ts
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Expand Up @@ -8,7 +8,7 @@

/* eslint-disable local/ban-types-eventually */

import {isError} from '@jest/expect-utils';
import {equals, isError, iterableEquality} from '@jest/expect-utils';
import {
EXPECTED_COLOR,
MatcherHintOptions,
Expand Down Expand Up @@ -225,7 +225,9 @@ const toThrowExpectedObject = (
thrown: Thrown | null,
expected: Error,
): SyncExpectationResult => {
const pass = thrown !== null && thrown.message === expected.message;
const pass =
thrown !== null &&
equals(thrown.value, expected, [iterableEquality], !thrown.isError);

const message = pass
? () =>
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