[coverage] Expose filterIgnored function

[liamappelbe]

package:coverage ignores lines that have // coverage:ignore-... comments, but for historical reasons this filtering is only applied during the formatting phase, when JSON coverage data is converted to LCOV etc. Specifically, there's a flag in the parseJson function that applies this filtering.

This PR pulls that functionality out into its own API function, filterIgnored. That way, clients can apply this filtering to their coverage data without converting it to JSON and back.

While I was at it, I also rewrote the algorithm that determines if a line is ignored. Previously it was a somewhat brittle stateful algorithm involving advancing a line range iterator while iterating through the hitmap (which also made potentially unsafe assumptions about the iteration order of the map). Now it's a simple binary search.

There was also some weird special casing for how // coverage:ignore-file was parsed by getIgnoredLines, where it would indicate that the whole file is ignored by returning [[0, lines.length]]. The caller (parseJsonSync) would immediately check for this return value and replace it with null to represent that the file should be skipped. Better to just return null from getIgnoredLines.

Part of dart-lang/test#2511

[github-actions]

Package publishing

Package	Version	Status	Publish tag (post-merge)
package:bazel_worker	1.1.3	already published at pub.dev
package:benchmark_harness	2.4.0-wip	WIP (no publish necessary)
package:boolean_selector	2.1.2	already published at pub.dev
package:browser_launcher	1.1.3	already published at pub.dev
package:cli_config	0.2.1-wip	WIP (no publish necessary)
package:cli_util	0.4.2	already published at pub.dev
package:clock	1.1.3-wip	WIP (no publish necessary)
package:code_builder	4.10.2-wip	WIP (no publish necessary)
package:coverage	1.15.0	ready to publish	coverage-v1.15.0
package:csslib	1.0.2	already published at pub.dev
package:extension_discovery	2.1.0	already published at pub.dev
package:file	7.0.2-wip	WIP (no publish necessary)
package:file_testing	3.1.0-wip	WIP (no publish necessary)
package:glob	2.1.3	already published at pub.dev
package:graphs	2.3.3-wip	WIP (no publish necessary)
package:html	0.15.6	already published at pub.dev
package:io	1.1.0-wip	WIP (no publish necessary)
package:json_rpc_2	4.0.0	already published at pub.dev
package:markdown	7.3.1-wip	WIP (no publish necessary)
package:mime	2.0.0	already published at pub.dev
package:oauth2	2.0.4-wip	WIP (no publish necessary)
package:package_config	2.3.0-wip	WIP (no publish necessary)
package:pool	1.5.2-wip	WIP (no publish necessary)
package:process	5.0.4	already published at pub.dev
package:pub_semver	2.2.0	already published at pub.dev
package:pubspec_parse	1.5.0	already published at pub.dev
package:source_map_stack_trace	2.1.3-wip	WIP (no publish necessary)
package:source_maps	0.10.14-wip	WIP (no publish necessary)
package:source_span	1.10.1	already published at pub.dev
package:sse	4.1.8	already published at pub.dev
package:stack_trace	1.12.1	already published at pub.dev
package:stream_channel	2.1.4	already published at pub.dev
package:stream_transform	2.1.2-wip	WIP (no publish necessary)
package:string_scanner	1.4.1	already published at pub.dev
package:term_glyph	1.2.3-wip	WIP (no publish necessary)
package:test_reflective_loader	0.3.0	ready to publish	test_reflective_loader-v0.3.0
package:timing	1.0.2	already published at pub.dev
package:unified_analytics	8.0.3	ready to publish	unified_analytics-v8.0.3
package:watcher	1.1.2	already published at pub.dev
package:yaml	3.1.3	already published at pub.dev
package:yaml_edit	2.2.2	already published at pub.dev

Documentation at https://github.com/dart-lang/ecosystem/wiki/Publishing-automation.

[github-actions]

PR Health

Breaking changes ⚠️

Package	Change	Current Version	New Version	Needed Version	Looking good?
coverage	Breaking	1.14.1	1.15.0	2.0.0 Got "1.15.0" expected >= "2.0.0" (breaking changes)	⚠️

This check can be disabled by tagging the PR with skip-breaking-check.

Changelog Entry ✔️

Package	Changed Files

Changes to files need to be accounted for in their respective changelogs.

Coverage ✔️

File	Coverage
pkgs/coverage/lib/src/hitmap.dart	💚 91 % ⬆️ 0 %
pkgs/coverage/lib/src/util.dart	💚 100 %

This check for test coverage is informational (issues shown here will not fail the PR).

API leaks ⚠️

The following packages contain symbols visible in the public API, but not exported by the library. Export these symbols or remove them from your publicly visible API.

Package	Leaked API symbols
coverage	_CoverageInfo

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License Headers ✔️

// Copyright (c) 2025, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

Files
no missing headers

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Unrelated files missing license headers

Files
pkgs/bazel_worker/benchmark/benchmark.dart
pkgs/bazel_worker/example/client.dart
pkgs/bazel_worker/example/worker.dart
pkgs/benchmark_harness/integration_test/perf_benchmark_test.dart
pkgs/boolean_selector/example/example.dart
pkgs/clock/lib/clock.dart
pkgs/clock/lib/src/clock.dart
pkgs/clock/lib/src/default.dart
pkgs/clock/lib/src/stopwatch.dart
pkgs/clock/lib/src/utils.dart
pkgs/clock/test/clock_test.dart
pkgs/clock/test/default_test.dart
pkgs/clock/test/stopwatch_test.dart
pkgs/clock/test/utils.dart
pkgs/coverage/lib/src/coverage_options.dart
pkgs/html/example/main.dart
pkgs/html/lib/dom.dart
pkgs/html/lib/dom_parsing.dart
pkgs/html/lib/html_escape.dart
pkgs/html/lib/parser.dart
pkgs/html/lib/src/constants.dart
pkgs/html/lib/src/encoding_parser.dart
pkgs/html/lib/src/html_input_stream.dart
pkgs/html/lib/src/list_proxy.dart
pkgs/html/lib/src/query_selector.dart
pkgs/html/lib/src/token.dart
pkgs/html/lib/src/tokenizer.dart
pkgs/html/lib/src/treebuilder.dart
pkgs/html/lib/src/utils.dart
pkgs/html/test/dom_test.dart
pkgs/html/test/parser_feature_test.dart
pkgs/html/test/parser_test.dart
pkgs/html/test/query_selector_test.dart
pkgs/html/test/selectors/level1_baseline_test.dart
pkgs/html/test/selectors/level1_lib.dart
pkgs/html/test/selectors/selectors.dart
pkgs/html/test/support.dart
pkgs/html/test/tokenizer_test.dart
pkgs/html/test/trie_test.dart
pkgs/html/tool/generate_trie.dart
pkgs/pubspec_parse/test/git_uri_test.dart
pkgs/stack_trace/example/example.dart
pkgs/watcher/test/custom_watcher_factory_test.dart
pkgs/yaml_edit/example/example.dart

[coveralls]

Pull Request Test Coverage Report for Build 16134020033

Details

• 34 of 34 (100.0%) changed or added relevant lines in 2 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage increased (+0.1%) to 93.927%

---

Files with Coverage Reduction	New Missed Lines	%
pkgs/coverage/lib/src/hitmap.dart	1	91.3%

Totals
Change from base Build 16093549360:	0.1%
Covered Lines:	696
Relevant Lines:	741

---

💛 - Coveralls

[bkonyi]

Is there any chance that this[0].isEmpty?