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assert: fix deepEqual similar sets and maps bug #13426

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@josephg josephg commented Jun 3, 2017

This fixes a bug where deepEqual and deepStrictEqual would have
incorrect behaviour in sets and maps containing multiple equivalent
keys.

Fixes: #13347
Refs: #12142

Checklist
  • make -j4 test (UNIX), or vcbuild test (Windows) passes
  • tests and/or benchmarks are included
  • commit message follows commit guidelines
Affected core subsystem(s)

assert

This fixes a bug where deepEqual and deepStrictEqual would have
incorrect behaviour in sets and maps containing multiple equivalent
keys.

Fixes: nodejs#13347
Refs: nodejs#12142
@nodejs-github-bot nodejs-github-bot added the assert Issues and PRs related to the assert subsystem. label Jun 3, 2017
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LGTM % nits & CI

@@ -187,6 +187,20 @@ assertOnlyDeepEqual(new Map([['a', '1']]), new Map([['a', 1]]));

assertDeepAndStrictEqual(new Set([{}]), new Set([{}]));

// Discussion of these test cases here - https://github.com/nodejs/node/issues/13347
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nit: just put Ref: https://github.com/nodejs/node/issues/13347

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Done

lib/assert.js Outdated
// This is a set of the entries in b which have been consumed in our pairwise
// comparison. Initialized lazily so sets which only have value types can
// skip an extra allocation.
let bEntriesUsed = null;
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nit: I'd rather you name it something like usedEntries, since bEntriesUsed sounds like a boolean predicating a need to use .entries()

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If you choose to accept this nit, rename everywhere else as well...

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Sure - I don't have a strong opinion so I've renamed it.

My concern with usedEntries is that it doesn't make it clear that we're marking entries in set b.

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refack commented Jun 3, 2017

lib/assert.js Outdated
for (const val1 of a) {
// If the value doesn't exist in the second set by reference, and its an
// object or an array we'll need to go hunting for something thats
// deep-equal to it. Note that this is O(n^2) complexity, and will get
// slower if large, very similar sets / maps are nested inside.
// Unfortunately there's no real way around this.
if (!setHasSimilarElement(b, val1, strict, memo)) {
if (bEntriesUsed == null && typeof val1 === 'object')
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Why is it important that a current val1 is an object? And why it should prevent initializing bEntriesUsed "for now" if it is not?

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The bug doesn't affect value types because its impossible for two strings, numbers, bools, etc to be deepEqual to one another without being reference-equal. So in the case where the set or map only contains value typed entries, there's no need to allocate an extra set for bEntriesUsed.

Lazily allocating the set when needed is a microoptimization.

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Then maybe it worth to continue that optimization and checking type of val2 before adding it to set of usedEntries? Because presence of even single object in a set with large number of typed entries would lead to adding them to usedEntries without any need.

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Maybe.. but in practice its very rare to mix types in set / map keys. And it still won't matter in strict mode because there's an early return for value types anyway.

Uhhhh but not in non-strict mode. Huh - looks like this also doesn't throw:

assert.deepEqual(new Set([3, '3']), new Set([3, 4]));

fixes

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... Fixed. PR updated so this behaves correctly too.

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💯

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refack commented Jun 3, 2017

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refack commented Jun 3, 2017

Lint errors:

not ok 27 - /usr/home/iojs/build/workspace/node-test-linter/test/parallel/test-assert-deep.js
  ---
  message: Missing space before value for key 'a'.
  severity: error
  data:
    line: 208
    column: 15
    ruleId: key-spacing
  messages:
    - message: Missing space before value for key 'a'.
      severity: error
      data:
        line: 208
        column: 22
        ruleId: key-spacing
    - message: Missing space before value for key 'a'.
      severity: error
      data:
        line: 208
        column: 29
        ruleId: key-spacing
    - message: Missing space before value for key 'a'.
      severity: error
      data:
        line: 209
        column: 15
        ruleId: key-spacing
    - message: Missing space before value for key 'a'.
      severity: error
      data:
        line: 209
        column: 22
        ruleId: key-spacing
    - message: Missing space before value for key 'a'.
      severity: error
      data:
        line: 209
        column: 29
        ruleId: key-spacing
  ...

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josephg commented Jun 3, 2017

Oops! Sorry about that. Fixed!

$ make lint
Running JS linter...
./node tools/eslint/bin/eslint.js --cache --rulesdir=tools/eslint-rules --ext=.js,.md \
	  benchmark doc lib test tools
Running C++ linter...
Total errors found: 0

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refack commented Jun 4, 2017

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refack commented Jun 4, 2017

Linux CI fail was infrastructure related, but still rerunning: https://ci.nodejs.org/job/node-test-commit-linux/10349/

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josephg commented Jun 5, 2017

Unless there's any more comments, I think this is ready to merge 👓

@refack refack self-assigned this Jun 5, 2017
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refack commented Jun 5, 2017

I'll land this later today (let PDT people a last chance to chime in)
/cc @nodejs/testing

refack pushed a commit to refack/node that referenced this pull request Jun 5, 2017
This fixes a bug where deepEqual and deepStrictEqual would have
incorrect behaviour in sets and maps containing multiple equivalent
keys.

PR-URL: nodejs#13426
Fixes: nodejs#13347
Refs: nodejs#12142
Reviewed-By: Refael Ackermann <[email protected]>
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refack commented Jun 5, 2017

landed in 7cddcc9

@refack refack closed this Jun 5, 2017
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refack commented Jun 5, 2017

Extra quick sanity of master: https://ci.nodejs.org/job/node-test-commit-linuxone/6404/

@josephg josephg deleted the deepequal-bug branch June 5, 2017 22:40
jasnell pushed a commit that referenced this pull request Jun 7, 2017
This fixes a bug where deepEqual and deepStrictEqual would have
incorrect behaviour in sets and maps containing multiple equivalent
keys.

PR-URL: #13426
Fixes: #13347
Refs: #12142
Reviewed-By: Refael Ackermann <[email protected]>
@gibfahn gibfahn mentioned this pull request Jun 15, 2017
3 tasks
@refack refack removed their assignment Oct 20, 2018
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assert: deepEqual of two Sets with different content passes
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