Cleanup iterator helpers by jedel1043 · Pull Request #5236 · boa-dev/boa

jedel1043 · 2026-03-23T09:47:23Z

Kinda big refactor of our iterator helpers, but this makes it such that they reuse the same coroutine machinery that Array.fromAsync uses, removing many of the expect calls that were in place, which was a consequence of having to use an enum to represent all iterator helpers.

This also cleans up the intrinsic initialization code, which was kinda wrong in some places and caused a bug where the iterator returned by generator functions wouldn't have the iterator prototype setup correctly.

This puts us at 100% conformance (not counting joint iterators) for the Iterator.prototype suite BTW

github-actions · 2026-03-23T10:05:42Z

Test262 conformance changes

Test result	main count	PR count	difference
Total	52,963	52,963	0
Passed	50,545	50,732	+187
Ignored	1,426	1,426	0
Failed	992	805	-187
Panics	2	0	-2
Conformance	95.43%	95.79%	+0.35%

Fixed tests (187):

test/built-ins/Iterator/prototype/some/iterator-already-exhausted.js (previously Failed)
test/built-ins/Iterator/prototype/some/predicate-returns-non-boolean.js (previously Failed)
test/built-ins/Iterator/prototype/some/predicate-this.js (previously Failed)
test/built-ins/Iterator/prototype/some/predicate-returns-falsey.js (previously Failed)
test/built-ins/Iterator/prototype/some/predicate-returns-truthy.js (previously Failed)
test/built-ins/Iterator/prototype/some/predicate-args.js (previously Failed)
test/built-ins/Iterator/prototype/some/predicate-returns-falsey-then-truthy.js (previously Failed)
test/built-ins/Iterator/prototype/some/iterator-has-no-return.js (previously Failed)
test/built-ins/Iterator/prototype/some/argument-validation-failure-closes-underlying.js (previously Failed)
test/built-ins/Iterator/prototype/some/argument-effect-order.js (previously Failed)
test/built-ins/Iterator/prototype/some/callable.js (previously Failed)
test/built-ins/Iterator/prototype/some/result-is-boolean.js (previously Failed)
test/built-ins/Iterator/prototype/reduce/reducer-args-no-initial-value.js (previously Failed)
test/built-ins/Iterator/prototype/reduce/reducer-args-initial-value.js (previously Failed)
test/built-ins/Iterator/prototype/reduce/reducer-this.js (previously Failed)
test/built-ins/Iterator/prototype/reduce/iterator-yields-once-initial-value.js (previously Failed)
test/built-ins/Iterator/prototype/reduce/iterator-already-exhausted-initial-value.js (previously Failed)
test/built-ins/Iterator/prototype/reduce/argument-validation-failure-closes-underlying.js (previously Failed)
test/built-ins/Iterator/prototype/reduce/argument-effect-order.js (previously Failed)
test/built-ins/Iterator/prototype/reduce/callable.js (previously Failed)
test/built-ins/Iterator/prototype/reduce/non-callable-reducer.js (previously Failed)
test/built-ins/Iterator/prototype/reduce/iterator-already-exhausted-no-initial-value.js (previously Failed)
test/built-ins/Iterator/prototype/reduce/reducer-memo-can-be-any-type.js (previously Failed)
test/built-ins/Iterator/prototype/reduce/iterator-yields-once-no-initial-value.js (previously Failed)
test/built-ins/Iterator/prototype/constructor/weird-setter.js (previously Failed)
test/built-ins/Iterator/prototype/find/iterator-already-exhausted.js (previously Failed)
test/built-ins/Iterator/prototype/find/predicate-returns-non-boolean.js (previously Failed)
test/built-ins/Iterator/prototype/find/predicate-this.js (previously Failed)
test/built-ins/Iterator/prototype/find/predicate-returns-falsey.js (previously Failed)
test/built-ins/Iterator/prototype/find/predicate-returns-truthy.js (previously Failed)
test/built-ins/Iterator/prototype/find/predicate-args.js (previously Failed)
test/built-ins/Iterator/prototype/find/predicate-returns-falsey-then-truthy.js (previously Failed)
test/built-ins/Iterator/prototype/find/iterator-has-no-return.js (previously Failed)
test/built-ins/Iterator/prototype/find/argument-validation-failure-closes-underlying.js (previously Failed)
test/built-ins/Iterator/prototype/find/argument-effect-order.js (previously Failed)
test/built-ins/Iterator/prototype/find/callable.js (previously Failed)
test/built-ins/Iterator/prototype/map/returned-iterator-yields-mapper-return-values.js (previously Failed)
test/built-ins/Iterator/prototype/map/iterator-already-exhausted.js (previously Failed)
test/built-ins/Iterator/prototype/map/throws-typeerror-when-generator-is-running.js (previously Failed)
test/built-ins/Iterator/prototype/map/mapper-args.js (previously Failed)
test/built-ins/Iterator/prototype/map/mapper-this.js (previously Failed)
test/built-ins/Iterator/prototype/map/result-is-iterator.js (previously Failed)
test/built-ins/Iterator/prototype/map/underlying-iterator-advanced-in-parallel.js (previously Failed)
test/built-ins/Iterator/prototype/map/argument-validation-failure-closes-underlying.js (previously Failed)
test/built-ins/Iterator/prototype/map/argument-effect-order.js (previously Failed)
test/built-ins/Iterator/prototype/map/underlying-iterator-closed.js (previously Failed)
test/built-ins/Iterator/prototype/map/underlying-iterator-closed-in-parallel.js (previously Failed)
test/built-ins/Iterator/prototype/map/callable.js (previously Failed)
test/built-ins/Iterator/prototype/flatMap/flattens-iterator.js (previously Failed)
test/built-ins/Iterator/prototype/flatMap/iterator-already-exhausted.js (previously Failed)
test/built-ins/Iterator/prototype/flatMap/flattens-iterable.js (previously Failed)
test/built-ins/Iterator/prototype/flatMap/iterable-to-iterator-fallback.js (previously Failed)
test/built-ins/Iterator/prototype/flatMap/throws-typeerror-when-generator-is-running.js (previously Failed)
test/built-ins/Iterator/prototype/flatMap/mapper-args.js (previously Failed)
test/built-ins/Iterator/prototype/flatMap/flattens-only-depth-1.js (previously Failed)
test/built-ins/Iterator/prototype/flatMap/mapper-this.js (previously Failed)
test/built-ins/Iterator/prototype/flatMap/result-is-iterator.js (previously Failed)
test/built-ins/Iterator/prototype/flatMap/underlying-iterator-advanced-in-parallel.js (previously Failed)
test/built-ins/Iterator/prototype/flatMap/return-is-forwarded-to-mapper-result.js (previously Failed)
test/built-ins/Iterator/prototype/flatMap/argument-validation-failure-closes-underlying.js (previously Failed)
test/built-ins/Iterator/prototype/flatMap/argument-effect-order.js (previously Failed)
test/built-ins/Iterator/prototype/flatMap/mapper-returns-closed-iterator.js (previously Failed)
test/built-ins/Iterator/prototype/flatMap/mapper-returns-non-object.js (previously Failed)
test/built-ins/Iterator/prototype/flatMap/underlying-iterator-closed.js (previously Failed)
test/built-ins/Iterator/prototype/flatMap/underlying-iterator-closed-in-parallel.js (previously Failed)
test/built-ins/Iterator/prototype/flatMap/callable.js (previously Failed)
test/built-ins/Iterator/prototype/flatMap/iterable-primitives-are-not-flattened.js (previously Failed)
test/built-ins/Iterator/prototype/flatMap/strings-are-not-flattened.js (previously Failed)
test/built-ins/Iterator/prototype/every/iterator-already-exhausted.js (previously Failed)
test/built-ins/Iterator/prototype/every/predicate-returns-non-boolean.js (previously Failed)
test/built-ins/Iterator/prototype/every/predicate-this.js (previously Failed)
test/built-ins/Iterator/prototype/every/predicate-returns-falsey.js (previously Failed)
test/built-ins/Iterator/prototype/every/predicate-returns-truthy.js (previously Failed)
test/built-ins/Iterator/prototype/every/predicate-args.js (previously Failed)
test/built-ins/Iterator/prototype/every/iterator-has-no-return.js (previously Failed)
test/built-ins/Iterator/prototype/every/argument-validation-failure-closes-underlying.js (previously Failed)
test/built-ins/Iterator/prototype/every/argument-effect-order.js (previously Failed)
test/built-ins/Iterator/prototype/every/callable.js (previously Failed)
test/built-ins/Iterator/prototype/every/result-is-boolean.js (previously Failed)
test/built-ins/Iterator/prototype/every/predicate-returns-truthy-then-falsey.js (previously Failed)
test/built-ins/Iterator/prototype/forEach/fn-called-for-each-yielded-value.js (previously Failed)
test/built-ins/Iterator/prototype/forEach/iterator-already-exhausted.js (previously Failed)
test/built-ins/Iterator/prototype/forEach/fn-this.js (previously Failed)
test/built-ins/Iterator/prototype/forEach/result-is-undefined.js (previously Failed)
test/built-ins/Iterator/prototype/forEach/argument-validation-failure-closes-underlying.js (previously Failed)
test/built-ins/Iterator/prototype/forEach/argument-effect-order.js (previously Failed)
test/built-ins/Iterator/prototype/forEach/callable.js (previously Failed)
test/built-ins/Iterator/prototype/forEach/fn-args.js (previously Failed)
test/built-ins/Iterator/prototype/filter/iterator-already-exhausted.js (previously Failed)
test/built-ins/Iterator/prototype/filter/predicate-returns-non-boolean.js (previously Failed)
test/built-ins/Iterator/prototype/filter/predicate-this.js (previously Failed)
test/built-ins/Iterator/prototype/filter/predicate-args.js (previously Failed)
test/built-ins/Iterator/prototype/filter/throws-typeerror-when-generator-is-running.js (previously Failed)
test/built-ins/Iterator/prototype/filter/result-is-iterator.js (previously Failed)
test/built-ins/Iterator/prototype/filter/underlying-iterator-advanced-in-parallel.js (previously Failed)
test/built-ins/Iterator/prototype/filter/predicate-filters.js (previously Failed)
test/built-ins/Iterator/prototype/filter/argument-validation-failure-closes-underlying.js (previously Failed)
test/built-ins/Iterator/prototype/filter/argument-effect-order.js (previously Failed)
test/built-ins/Iterator/prototype/filter/underlying-iterator-closed.js (previously Failed)
test/built-ins/Iterator/prototype/filter/underlying-iterator-closed-in-parallel.js (previously Failed)
test/built-ins/Iterator/prototype/filter/callable.js (previously Failed)
test/built-ins/Iterator/prototype/drop/limit-greater-than-total.js (previously Failed)
test/built-ins/Iterator/prototype/drop/limit-rangeerror.js (previously Failed)
test/built-ins/Iterator/prototype/drop/limit-equals-total.js (previously Failed)
test/built-ins/Iterator/prototype/drop/throws-typeerror-when-generator-is-running.js (previously Panic)
test/built-ins/Iterator/prototype/drop/result-is-iterator.js (previously Failed)
test/built-ins/Iterator/prototype/drop/underlying-iterator-advanced-in-parallel.js (previously Failed)
test/built-ins/Iterator/prototype/drop/argument-validation-failure-closes-underlying.js (previously Failed)
test/built-ins/Iterator/prototype/drop/argument-effect-order.js (previously Failed)
test/built-ins/Iterator/prototype/drop/limit-tonumber-throws.js (previously Failed)
test/built-ins/Iterator/prototype/drop/underlying-iterator-closed.js (previously Failed)
test/built-ins/Iterator/prototype/drop/underlying-iterator-closed-in-parallel.js (previously Failed)
test/built-ins/Iterator/prototype/drop/callable.js (previously Failed)
test/built-ins/Iterator/prototype/drop/limit-tonumber.js (previously Failed)
test/built-ins/Iterator/prototype/drop/limit-less-than-total.js (previously Failed)
test/built-ins/Iterator/prototype/Symbol.toStringTag/weird-setter.js (previously Failed)
test/built-ins/Iterator/prototype/take/limit-rangeerror.js (previously Failed)
test/built-ins/Iterator/prototype/take/throws-typeerror-when-generator-is-running.js (previously Panic)
test/built-ins/Iterator/prototype/take/result-is-iterator.js (previously Failed)
test/built-ins/Iterator/prototype/take/underlying-iterator-advanced-in-parallel.js (previously Failed)
test/built-ins/Iterator/prototype/take/limit-greater-than-or-equal-to-total.js (previously Failed)
test/built-ins/Iterator/prototype/take/argument-validation-failure-closes-underlying.js (previously Failed)
test/built-ins/Iterator/prototype/take/argument-effect-order.js (previously Failed)
test/built-ins/Iterator/prototype/take/limit-tonumber-throws.js (previously Failed)
test/built-ins/Iterator/prototype/take/underlying-iterator-closed.js (previously Failed)
test/built-ins/Iterator/prototype/take/underlying-iterator-closed-in-parallel.js (previously Failed)
test/built-ins/Iterator/prototype/take/callable.js (previously Failed)
test/built-ins/Iterator/prototype/take/limit-tonumber.js (previously Failed)
test/built-ins/Iterator/prototype/take/limit-less-than-total.js (previously Failed)
test/built-ins/Iterator/prototype/toArray/iterator-already-exhausted.js (previously Failed)
test/built-ins/Iterator/prototype/toArray/callable.js (previously Failed)
test/built-ins/Iterator/from/iterable-primitives.js (previously Failed)
test/built-ins/Iterator/from/result-proto.js (previously Failed)
test/built-ins/Iterator/concat/throws-typeerror-when-generator-is-running-return.js (previously Failed)
test/built-ins/Object/prototype/toString/symbol-tag-map-builtin.js (previously Failed)
test/built-ins/Object/prototype/toString/symbol-tag-set-builtin.js (previously Failed)
test/built-ins/Object/prototype/toString/symbol-tag-array-builtin.js (previously Failed)
test/built-ins/Object/prototype/toString/symbol-tag-string-builtin.js (previously Failed)
test/staging/sm/Iterator/prototype/lazy-methods-handle-empty-iterators.js (previously Failed)
test/staging/sm/Iterator/prototype/lazy-methods-reentry-not-close-iterator.js (previously Failed)
test/staging/sm/Iterator/prototype/iterator-helper-methods-throw-on-generators.js (previously Failed)
test/staging/sm/Iterator/prototype/generator-methods-throw-on-iterator-helpers.js (previously Failed)
test/staging/sm/Iterator/prototype/iterator-helpers-from-other-global.js (previously Failed)
test/staging/sm/Iterator/prototype/take-drop-throw-eagerly-on-negative.js (previously Failed)
test/staging/sm/Iterator/prototype/lazy-methods-throw-on-reentry.js (previously Failed)
test/staging/sm/Iterator/prototype/some/coerce-result-to-boolean.js (previously Failed)
test/staging/sm/Iterator/prototype/some/return-false-if-none-match.js (previously Failed)
test/staging/sm/Iterator/prototype/some/check-fn-after-getting-iterator.js (previously Failed)
test/staging/sm/Iterator/prototype/some/short-circuit-on-true.js (previously Failed)
test/staging/sm/Iterator/prototype/reduce/iterator-empty-return-initial-value.js (previously Failed)
test/staging/sm/Iterator/prototype/reduce/left-associative.js (previously Failed)
test/staging/sm/Iterator/prototype/reduce/no-initial-value-set-accumulator-to-first-value.js (previously Failed)
test/staging/sm/Iterator/prototype/reduce/check-fn-after-getting-iterator.js (previously Failed)
test/staging/sm/Iterator/prototype/reduce/reduce.js (previously Failed)
test/staging/sm/Iterator/prototype/reduce/accumulator-set-to-initial-value.js (previously Failed)
test/staging/sm/Iterator/prototype/find/short-circuit-on-match.js (previously Failed)
test/staging/sm/Iterator/prototype/find/coerce-result-to-boolean.js (previously Failed)
test/staging/sm/Iterator/prototype/find/check-fn-after-getting-iterator.js (previously Failed)
test/staging/sm/Iterator/prototype/find/return-undefined-if-none-match.js (previously Failed)
test/staging/sm/Iterator/prototype/map/interleaved-map-calls.js (previously Failed)
test/staging/sm/Iterator/prototype/map/call-next-on-iterator-while-iterating.js (previously Failed)
test/staging/sm/Iterator/prototype/map/reenter-map-generator-from-mapper.js (previously Failed)
test/staging/sm/Iterator/prototype/map/clobber-symbol.js (previously Failed)
test/staging/sm/Iterator/prototype/map/mutate-iterator.js (previously Failed)
test/staging/sm/Iterator/prototype/map/mutate-iterator-after-done.js (previously Failed)
test/staging/sm/Iterator/prototype/map/output-at-generator-end.js (previously Failed)
test/staging/sm/Iterator/prototype/flatMap/inner-generator.js (previously Failed)
test/staging/sm/Iterator/prototype/flatMap/inner-empty-iterable.js (previously Failed)
test/staging/sm/Iterator/prototype/flatMap/throw-when-inner-not-iterable.js (previously Failed)
test/staging/sm/Iterator/prototype/flatMap/close-iterator-when-inner-value-throws.js (previously Failed)
test/staging/sm/Iterator/prototype/flatMap/close-iterator-when-inner-complete-throws.js (previously Failed)
test/staging/sm/Iterator/prototype/flatMap/close-iterator-when-inner-next-throws.js (previously Failed)
test/staging/sm/Iterator/prototype/every/short-circuit-on-false.js (previously Failed)
test/staging/sm/Iterator/prototype/every/coerce-result-to-boolean.js (previously Failed)
test/staging/sm/Iterator/prototype/every/check-fn-after-getting-iterator.js (previously Failed)
test/staging/sm/Iterator/prototype/every/return-true-if-all-match.js (previously Failed)
test/staging/sm/Iterator/prototype/forEach/forEach.js (previously Failed)
test/staging/sm/Iterator/prototype/forEach/check-fn-after-getting-iterator.js (previously Failed)
test/staging/sm/Iterator/prototype/filter/coerce-result-to-boolean.js (previously Failed)
test/staging/sm/Iterator/prototype/drop/drop-more-than-available.js (previously Failed)
test/staging/sm/Iterator/prototype/take/take-more-than-available.js (previously Failed)
test/staging/sm/Iterator/prototype/toArray/toArray.js (previously Failed)
test/staging/sm/Iterator/prototype/toArray/iterator-empty.js (previously Failed)
test/staging/sm/Iterator/prototype/toArray/create-in-current-realm.js (previously Failed)
test/staging/sm/Iterator/from/return-iterator-if-iterable.js (previously Failed)
test/staging/sm/Iterator/from/wrap-new-global.js (previously Failed)
test/staging/sm/Array/from_primitive.js (previously Failed)

Tested main commit: 5b0f62ad860a2f5e2a4631ac2f280642cf7e21ea
Tested PR commit: 48378f0de1025cde349d649043a0f8c39dc03750
Compare commits: 5b0f62a...48378f0

codecov · 2026-03-23T11:11:46Z

Codecov Report

❌ Patch coverage is 68.33811% with 221 lines in your changes missing coverage. Please review.
✅ Project coverage is 59.80%. Comparing base (6ddc2b4) to head (48378f0).
⚠️ Report is 918 commits behind head on main.

Files with missing lines	Patch %	Lines
core/engine/src/builtins/array/from_async.rs	0.00%	88 Missing ⚠️
...engine/src/builtins/iterable/iterator_prototype.rs	73.56%	69 Missing ⚠️
.../src/builtins/iterable/iterator_helper/flat_map.rs	76.11%	16 Missing ⚠️
core/engine/src/object/builtins/jspromise.rs	0.00%	15 Missing ⚠️
...ngine/src/builtins/iterable/iterator_helper/mod.rs	88.13%	7 Missing ⚠️
...gine/src/builtins/iterable/iterator_helper/drop.rs	82.14%	5 Missing ⚠️
...ne/src/builtins/iterable/iterator_helper/concat.rs	87.87%	4 Missing ⚠️
...ne/src/builtins/iterable/iterator_helper/filter.rs	87.87%	4 Missing ⚠️
...gine/src/builtins/iterable/iterator_helper/take.rs	84.00%	4 Missing ⚠️
...ngine/src/builtins/iterable/iterator_helper/map.rs	87.50%	3 Missing ⚠️
... and 3 more

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #5236       +/-   ##
===========================================
+ Coverage   47.24%   59.80%   +12.55%     
===========================================
  Files         476      589      +113     
  Lines       46892    63407    +16515     
===========================================
+ Hits        22154    37918    +15764     
- Misses      24738    25489      +751

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nekevss

Had a couple nits regarding the docs. But nothing blocking.

LGTM!

core/engine/src/builtins/iterable/iterator_prototype.rs

jedel1043 requested a review from a team as a code owner March 23, 2026 09:47

github-actions bot added the Waiting On Review Waiting on reviews from the maintainers label Mar 23, 2026

github-actions bot added this to the v1.0.0 milestone Mar 23, 2026

github-actions bot added C-Builtins PRs and Issues related to builtins/intrinsics C-GC Issue related to garbage collection labels Mar 23, 2026

github-actions bot added the C-Tests Issues and PRs related to the tests. label Mar 23, 2026

jedel1043 mentioned this pull request Mar 23, 2026

feat: implement Iterator.zip and Iterator.zipKeyed (#4564) #4946

Open

Cleanup iterator helpers

b6feb72

jedel1043 force-pushed the cleanup-iterator-helpers branch from ae6798a to b6feb72 Compare March 23, 2026 22:36

nekevss approved these changes Mar 24, 2026

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Tweak docs

c875ec9

jedel1043 enabled auto-merge March 24, 2026 04:00

Tweak docs pt. 2

48378f0

jedel1043 added this pull request to the merge queue Mar 24, 2026

Merged via the queue into boa-dev:main with commit 8fcbfcb Mar 24, 2026
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jedel1043 deleted the cleanup-iterator-helpers branch March 24, 2026 04:48

github-actions bot removed the Waiting On Review Waiting on reviews from the maintainers label Mar 24, 2026

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Cleanup iterator helpers#5236
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