Made the bad lines exception print out the bad lines by gaaclarke · Pull Request #180909 · flutter/flutter

gaaclarke · 2026-01-13T17:23:17Z

adds better logging for debugging "bad line" failures

Pre-launch Checklist

I read the Contributor Guide and followed the process outlined there for submitting PRs.
I read the Tree Hygiene wiki page, which explains my responsibilities.
I read and followed the Flutter Style Guide, including Features we expect every widget to implement.
I signed the CLA.
I listed at least one issue that this PR fixes in the description above.
I updated/added relevant documentation (doc comments with ///).
I added new tests to check the change I am making, or this PR is test-exempt.
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gemini-code-assist

Code Review

This pull request improves the debugging experience for 'bad line' failures in flutter_test_performance.dart by including the actual problematic lines in the exception message instead of just a count. The implementation is sound. I have one suggestion to further improve the readability of the error output.

gemini-code-assist · 2026-01-13T17:24:46Z

+    const seperator = '\n  ';
+    throw Exception('flutter test rendered unexpected output ${badLines.join(seperator)}');


For better readability of the exception message, it's helpful to start the list of bad lines on a new line and ensure all of them are indented consistently. This makes the output cleaner and easier to parse visually.

Additionally, there's a typo in the variable name seperator; it should be separator.

Here's a more concise way to achieve this that addresses both points:

Suggested change

const seperator = '\n ';

throw Exception('flutter test rendered unexpected output ${badLines.join(seperator)}');

throw Exception('flutter test rendered unexpected output:\n ${badLines.join('\n ')}');

I like this one too

jtmcdole

nits - but prefixed by "thankyou!"

jtmcdole · 2026-01-13T17:37:59Z

      final Match? match = testOutputPattern.matchAsPrefix(entry);
      if (match == null) {
-        badLines += 1;
+        badLines.add(entry);


'badline(no match): $entry'

jtmcdole · 2026-01-13T17:38:14Z

          step = TestStep.testPassed;
        } else {
-          badLines += 1;
+          badLines.add(entry);


'badline(fallthrough): $entry'

jtmcdole · 2026-01-13T17:38:31Z

  ) {
    print('test stderr: $entry');
-    badLines += 1;
+    badLines.add(entry);


badline(stderr): $entry

jtmcdole · 2026-01-13T17:38:46Z

+    const seperator = '\n  ';
+    throw Exception('flutter test rendered unexpected output ${badLines.join(seperator)}');


I like this one too

auto-submit · 2026-01-13T18:05:25Z

autosubmit label was removed for flutter/flutter/180909, because - The status or check suite Linux analyze has failed. Please fix the issues identified (or deflake) before re-applying this label.

jtmcdole · 2026-01-13T23:37:36Z

  if (badLines.isNotEmpty) {
    const seperator = '\n  ';
-    throw Exception('flutter test rendered unexpected output ${badLines.join(seperator)}');
+    throw Exception('flutter test rendered unexpected output:$seperator${badLines.join(seperator)}');


I think it's complaining about this line.

throw Exception( 'flutter test rendered unexpected output:$seperator${badLines.join(seperator)}', );

jtmcdole · 2026-01-13T23:37:56Z

(still lgtm from me)

auto-submit · 2026-01-14T00:14:26Z

autosubmit label was removed for flutter/flutter/180909, because - The status or check suite Windows tool_integration_tests_8_9 has failed. Please fix the issues identified (or deflake) before re-applying this label.

…/flutter#180909)

Made the bad lines exception print out the bad lines

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gaaclarke requested a review from jtmcdole January 13, 2026 17:23

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Merged via the queue into flutter:master with commit 9aea438 Jan 14, 2026
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Roll Flutter from 793b0b89e82e to 9aea438bfcb9 (22 revisions) flutter/packages#10789

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Roll Flutter from 793b0b89e82e to bc63dfe662d6 (24 revisions) flutter/packages#10790

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Roll Flutter from 793b0b89e82e to 5e417dc81274 (25 revisions) flutter/packages#10791

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Roll Flutter from 793b0b89e82e to 5e417dc81274 (25 revisions) flutter/packages#10795

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Roll Flutter from b45a73b1dc3e to 3af33a0771e0 (41 revisions) flutter/packages#10804

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Roll Flutter from 48c247582e45 to 66b42dd1051a (50 revisions) flutter/packages#10818

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Roll Flutter from 48c247582e45 to 66b42dd1051a (50 revisions) flutter/packages#10819

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…/flutter#180909)

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…/flutter#180909)

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…/flutter#180909)

		const seperator = '\n ';
		throw Exception('flutter test rendered unexpected output ${badLines.join(seperator)}');

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gaaclarke commented Jan 13, 2026

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