Dart Log Failure Parser

Parse failures from Dart and Flutter test logs. Provides detailed patterns to detect and diagnose test failures.

Sby Skills Guide Bot
TestingIntermediate
308/29/2026
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#dart#flutter#log-parsing#test-failure#debugging

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name: dart-log-failure-parser description: Parse failures from Dart and Flutter test logs.

Dart Log Failure Parser

Workflow

1. Analyze Raw Log Output

Analyze the raw log output for failure details. Do not skim the output; check the entire log. The description of findings should include specific details for the failures (e.g., unformatted files, specific test names), not just the top-level command that failed.

2. Look for Failure Patterns

Pattern A: Error Blocks (e.g., Linux Analyze)

Search for blocks starting with ╡ERROR #. Example:

╔═╡ERROR #1╞════════════════════════════════════════════════════════════════════
║ Command: bin/cache/dart-sdk/bin/dart --enable-asserts /b/s/w/ir/x/w/flutter/dev/bots/analyze_snippet_code.dart --verbose
║ Command exited with exit code 255 but expected zero exit code.
║ Working directory: /b/s/w/ir/x/w/flutter
╚═══════════════════════════════════════════════════════════════════════════════

Pattern B: Task Result JSON

Search for "Task result:" followed by a JSON object. Example:

Task result:
{
  "success": false,
  "reason": "Task failed: PathNotFoundException: Cannot open file..."
}

Pattern C: Failing Tests List

For general Dart tests, look for a list at the end of the log starting with "Failing tests:". Example:

Failing tests:
  test/general.shard/cache_test.dart: FontSubset artifacts for all platforms on arm64 hosts
  test/general.shard/cache_test.dart: FontSubset artifacts on arm64 linux

Pattern D: Build Failures

For build failures (e.g., engine tests failing at compile time), look for the following indicators in the logs or API summaries:

  • Lines starting with FAILED: (indicates a Ninja target failed).
  • Compiler error messages (e.g., error:, fatal error:).
  • Linker error messages (e.g., undefined reference to).
  • Summary messages in the check-runs API output like 1 build failed: [<build_name>].
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