[tests] Fix startup logcat race in MonitorAdbLogcat - #12196
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jonathanpeppers merged 3 commits intoJul 21, 2026
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Process buffered adb logcat output before starting live monitoring so early startup lines are not missed when tests begin monitoring after app launch. Add focused unit tests for buffered logcat matching behavior. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: ae324e4e-c922-4429-8222-3e37164d1e43
Drop the extra helper unit-test file and keep the success flag as bool, while retaining the buffered logcat pre-scan behavior change in MonitorAdbLogcat. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: ae324e4e-c922-4429-8222-3e37164d1e43
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Pull request overview
This PR makes device-test logcat monitoring more reliable by having MonitorAdbLogcat() scan already-buffered logcat output before attaching to live adb logcat streaming, reducing flakiness when startup markers are emitted before monitoring begins.
Changes:
- Read buffered logcat output via
adb logcat -dand run the existing matcher against it before starting live monitoring. - Add
TryMatchLogcatOutput()to centralize “scan + write-to-file + predicate match” behavior for buffered logcat output.
Limit both buffered and live predicate evaluation to the first successful match and make TryMatchLogcatOutput private to reduce API surface. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: ae324e4e-c922-4429-8222-3e37164d1e43
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July 21, 2026 19:18
dalexsoto
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Jul 21, 2026
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Pull Request
MonitorAdbLogcat()previously only tailed liveadb logcatoutput. Several device tests start the app before monitoring begins, so startup lines could be emitted and missed before the tailer attached, causing intermittent failures like missingDisplayed/startup markers.This change makes
MonitorAdbLogcat()first read buffered logcat output withadb logcat -dand run the same matcher over those lines, then continue tailing live output. That keeps behavior centralized in the shared helper and avoids per-test delay/retry changes.MonitorAdbLogcat).