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Let Chrome choose its remote debugging port - #2778
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When Chrome runs with a remote debugging port, which happens with `--debug`, `--pause-after-load`, and `--coverage`, `_connect` listened to the process's stderr to wait for the "DevTools listening" line. The `Browser` base class listens to the same single-subscription stream to collect the browser output, and that second listen threw a `StateError` which was silently caught. Once `firstWhere` found the line it cancelled the subscription, which closes the pipe, so all of Chrome's stderr, including its console logging, was missing from the "Browser output" in load failures and timeouts. Rename the `output` list on `Browser` to `accumulatedOutput`, and add an `output` stream built with `Stream.multi` which replays the accumulated lines to each new listener and then forwards new lines. It closes when both stdout and stderr are done, when the browser is closed, or when starting or running the browser fails. In `Chrome`, `tryPort` now only reports which debugging port it used, and `_connect` is an instance method which reads that port and waits for the DevTools line on `output`. The tab connection and the remote debugger URL come from a single lazy `_connection` future in place of the two completers, started by the first read of `remoteDebuggerUrl` or `gatherCoverage`. `BrowserManager` reads `remoteDebuggerUrl` before it loads any suites, so coverage collection still starts before tests run, and the replay means a late start still sees the DevTools line. Drop the `StateError` catch in `drainOutput`. Nothing else listens to the process streams now, and a future second listener should fail loudly instead of losing output.
When debugging or collecting coverage, the runner picked a probably-unused port with `getUnusedPort` and passed it to Chrome with `--remote-debugging-port`. Chrome gives no reliable signal that it bound the port, so there was a window where another process could take it, and `tryPort` had to report the chosen port back through a completer for `_connect` to use. Pass `--remote-debugging-port=0` so Chrome binds an unused port itself, and read the port from the URL in the "DevTools listening on" line, which `_connect` already waits for. With no port to choose or pass along, `tryPort`, the port completer, and the private constructor go away, and `Chrome` has a plain generative constructor. `spawn` already falls back to the default Chrome settings. Update the fake Chrome test to report a fake DevTools server's port in its DevTools line, and check that connecting reaches that server and that Chrome is started with `--remote-debugging-port=0`.
sigurdm
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Oct 6, 2026
# Conflicts: # pkgs/test/lib/src/runner/browser/chrome.dart # pkgs/test/test/runner/browser/chrome_test.dart
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`Uri.port` is 0 when the URL has no port, which would turn into a confusing connection failure on port 0. Throw a `StateError` naming the line instead, which also covers a URL that does not parse.
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Revisions updated by `dart tools/rev_sdk_deps.dart`. dartdoc (https://github.com/dart-lang/dartdoc/compare/5eb0f2c..e1859cf): e1859cfc Fri Oct 9 14:53:01 2026 +0200 Sarah Zakarias Link a bare prefix only when it maps to exactly one library (dart-lang/dartdoc#4295) c48f6fb9 Fri Oct 9 14:25:42 2026 +0200 Sarah Zakarias Resolve prefixes through the analyzer's PrefixElement.scopeLibraries (dart-lang/dartdoc#4294) 3a6297e2 Wed Oct 7 12:56:14 2026 +0200 Sarah Zakarias Require analyzer 14.5.0 and bump to 9.0.10 (dart-lang/dartdoc#4292) ecosystem (https://github.com/dart-lang/ecosystem/compare/16dca7a..622ef61): 622ef61 Mon Oct 12 00:23:27 2026 -0700 Kevin Moore fix(firehose): enforce -wip on published versions and tighten changelog checks (dart-lang/ecosystem#467) 5576a85 Wed Oct 7 09:29:44 2026 +0200 Moritz Support use-flutter option in groundskeeper workflow (dart-lang/ecosystem#444) http (https://github.com/dart-lang/http/compare/585d433..23f8574): 23f8574 Thu Oct 8 23:27:25 2026 +0700 Cong Bang feat(http2): configurable receive windows and frame size (dart-lang/http#1999) 18051a6 Thu Oct 8 10:39:38 2026 +0200 Moritz Enable Flutter in Groundskeeper workflow for Flutter packages (dart-lang/http#2004) native (https://github.com/dart-lang/native/compare/a2a6179..10515af): 10515afca Mon Oct 12 12:21:52 2026 +0200 Daco Harkes [native_toolchain_c] Do not pass linker flags when compiling static libraries (dart-lang/native#3731) native is held back at 10515af, before dart-lang/native#3728, because it breaks the dartdev `dart install` native assets tests. See dart-lang/native#3743. test (https://github.com/dart-lang/test/compare/d749b10..30acb69): 30acb69e Mon Oct 12 12:42:54 2026 -0700 Nate Bosch Time out browser loads just before the suite load timeout (dart-lang/test#2786) 597a0326 Mon Oct 12 12:22:53 2026 -0700 Kevin Moore Fix misplaced changelog entries and remove no-op health check (dart-lang/test#2789) 0b6efee8 Mon Oct 12 12:16:29 2026 -0700 Nate Bosch [checks] Collapse nested subjects in condition descriptions (dart-lang/test#2784) 17c98493 Mon Oct 12 12:08:23 2026 -0700 Nate Bosch Follow symlinks in precompiled browser test directories (dart-lang/test#2787) 1cc813ec Fri Oct 9 11:59:56 2026 -0700 Nate Bosch [checks] Join nested collapsed subjects with "that" (dart-lang/test#2783) ada7b950 Thu Oct 8 12:03:42 2026 -0700 Nate Bosch Prepare to publish (dart-lang/test#2780) c4b165b3 Wed Oct 7 11:29:08 2026 -0700 Kevin Moore [checks] Require package:meta ^1.17.0 (dart-lang/test#2779) 4a363d70 Tue Oct 6 10:46:31 2026 -0700 Nate Bosch Let Chrome choose its remote debugging port (dart-lang/test#2778) 465d66ab Tue Oct 6 09:35:22 2026 -0700 Nate Bosch Keep Chrome stderr in the browser output when debugging (dart-lang/test#2777) tools (https://github.com/dart-lang/tools/compare/a66d517..2b54c71): 2b54c71af Mon Oct 12 10:16:45 2026 +0200 dart-ecosystem-bot[bot] [boring] Update BoringSSL to 3fed4f20 (dart-lang/tools#2655) 2337f995a Sat Oct 10 03:11:40 2026 +0300 Hasan Armoush [json_rpc_2] Add strictProtocolChecks parameter to Client (dart-lang/tools#2555) c65c69ed1 Fri Oct 9 08:54:25 2026 +0200 Moritz [boring] Move package:boring to dart-lang/tools (2/4): FFI helpers from package:webcrypto (dart-lang/tools#2615) a04e45491 Thu Oct 8 21:07:18 2026 -0700 Kevin Moore chore: wire package:api_summary and package:string_scanner PR auto-labeler (dart-lang/tools#2652) 8bdd4b92c Thu Oct 8 09:20:48 2026 +0200 Morgan :) [code_builder] Allow built_collection 6.x. (dart-lang/tools#2645) c16040d35 Wed Oct 7 17:30:08 2026 -0700 Kevin Moore [api_summary] Sort primary barrel first and experimental entry points last (v1.2.0) (dart-lang/tools#2619) b2d0780db Wed Oct 7 11:27:16 2026 -0700 Kevin Moore [stream_channel] Require package:async ^2.6.0 (dart-lang/tools#2644) 3ab7bf9d0 Wed Oct 7 11:35:27 2026 +0200 Moritz [boring] Move package:boring to dart-lang/tools (1/4): vendored BoringSSL, bindings and source build (dart-lang/tools#2614) 29df6348b Tue Oct 6 15:21:44 2026 -0700 Kevin Moore feat(coverage): support web coverage reports in test_with_coverage (dart-lang/tools#2448) Regenerate pkg/{analyzer,analyzer_plugin,analyzer_testing}/api.txt. The rolled package:api_summary v1.2.0 (dart-lang/tools#2619) sorts the primary barrel first and other entry points after it, so entries in these files are reordered. The APIs themselves are unchanged. Change-Id: Ie8ff19c5a981ea8ecee8939c75457986a947e0a7 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/563220 Reviewed-by: Samuel Rawlins <[email protected]> Auto-Submit: Nate Bosch <[email protected]> Reviewed-by: Paul Berry <[email protected]> Commit-Queue: Paul Berry <[email protected]>
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When debugging or collecting coverage, the runner picked a probably-unused
port with
getUnusedPortand passed it to Chrome with--remote-debugging-port. Chrome gives no reliable signal that it boundthe port, so there was a window where another process could take it, and
tryPorthad to report the chosen port back through a completer for_connectto use.Pass
--remote-debugging-port=0so Chrome binds an unused port itself,and read the port from the URL in the "DevTools listening on" line, which
_connectalready waits for. With no port to choose or pass along,tryPort, the port completer, and the private constructor go away, andChromehas a plain generative constructor.spawnalready falls backto the default Chrome settings.
Update the fake Chrome test to report a fake DevTools server's port in its
DevTools line, and check that connecting reaches that server and that
Chrome is started with
--remote-debugging-port=0.