Bug 239780 – A python error causes results.html to be missing from layout test results

• Component: Tools / Tests
• Status: NEW

[Simon Fraser (smfr)]

This EWS run <https://ews-build.webkit.org/#/builders/68/builds/13819/steps/17/logs/stdio> shows an error shutting down the simulator:

10:08:27.729 681 Removing device 'Managed 7'
10:08:27.897 681 "/usr/bin/xcrun simctl delete 3882575F-7118-4051-9D0F-105AEEC707AE" took 0.17s
TypeError raised: 'NoneType' object is not subscriptable
Traceback (most recent call last):
  File "/Volumes/Data/worker/iOS-15-Simulator-WK2-Tests-EWS/build/Tools/Scripts/webkitpy/layout_tests/run_webkit_tests.py", line 92, in main
    run_details = run(port, options, args, stderr)
  File "/Volumes/Data/worker/iOS-15-Simulator-WK2-Tests-EWS/build/Tools/Scripts/webkitpy/layout_tests/run_webkit_tests.py", line 495, in run
    run_details = manager.run(args)
  File "/Volumes/Data/worker/iOS-15-Simulator-WK2-Tests-EWS/build/Tools/Scripts/webkitpy/layout_tests/controllers/manager.py", line 413, in run
    temp_initial_results, temp_retry_results, temp_enabled_pixel_tests_in_retry = self._run_test_subset(test_inputs, device_type=device_type)
  File "/Volumes/Data/worker/iOS-15-Simulator-WK2-Tests-EWS/build/Tools/Scripts/webkitpy/layout_tests/controllers/manager.py", line 506, in _run_test_subset
    retry_results = self._run_tests(retry_test_inputs,
  File "/Volumes/Data/worker/iOS-15-Simulator-WK2-Tests-EWS/build/Tools/Scripts/webkitpy/layout_tests/controllers/manager.py", line 566, in _run_tests
    return self._runner.run_tests(self._expectations[device_type], new_test_inputs, num_workers, retrying, device_type)
  File "/Volumes/Data/worker/iOS-15-Simulator-WK2-Tests-EWS/build/Tools/Scripts/webkitpy/layout_tests/controllers/layout_test_runner.py", line 175, in run_tests
    pool.do(
  File "/Volumes/Data/worker/iOS-15-Simulator-WK2-Tests-EWS/build/Tools/Scripts/libraries/webkitcorepy/webkitcorepy/task_pool.py", line 400, in do
    result = function(*args, **kwargs)
  File "/Volumes/Data/worker/iOS-15-Simulator-WK2-Tests-EWS/build/Tools/Scripts/webkitpy/layout_tests/controllers/layout_test_runner.py", line 76, in run_shard
    return Worker.instance.run_tests(shard)
  File "/Volumes/Data/worker/iOS-15-Simulator-WK2-Tests-EWS/build/Tools/Scripts/webkitpy/layout_tests/controllers/layout_test_runner.py", line 318, in run_tests
    Worker.instance.run_test(input, shard.name)
  File "/Volumes/Data/worker/iOS-15-Simulator-WK2-Tests-EWS/build/Tools/Scripts/webkitpy/layout_tests/controllers/layout_test_runner.py", line 346, in run_test
    result = self._run_test_with_or_without_timeout(test_input, test_timeout_sec, stop_when_done)
  File "/Volumes/Data/worker/iOS-15-Simulator-WK2-Tests-EWS/build/Tools/Scripts/webkitpy/layout_tests/controllers/layout_test_runner.py", line 403, in _run_test_with_or_without_timeout
    return self._run_test_in_this_thread(test_input, stop_when_done)
  File "/Volumes/Data/worker/iOS-15-Simulator-WK2-Tests-EWS/build/Tools/Scripts/webkitpy/layout_tests/controllers/layout_test_runner.py", line 489, in _run_test_in_this_thread
    return self._run_single_test(self._driver, test_input, stop_when_done)
  File "/Volumes/Data/worker/iOS-15-Simulator-WK2-Tests-EWS/build/Tools/Scripts/webkitpy/layout_tests/controllers/layout_test_runner.py", line 492, in _run_single_test
    return single_test_runner.run_single_test(
  File "/Volumes/Data/worker/iOS-15-Simulator-WK2-Tests-EWS/build/Tools/Scripts/webkitpy/layout_tests/controllers/single_test_runner.py", line 48, in run_single_test
    return runner.run()
  File "/Volumes/Data/worker/iOS-15-Simulator-WK2-Tests-EWS/build/Tools/Scripts/webkitpy/layout_tests/controllers/single_test_runner.py", line 123, in run
    return self._run_reftest()
  File "/Volumes/Data/worker/iOS-15-Simulator-WK2-Tests-EWS/build/Tools/Scripts/webkitpy/layout_tests/controllers/single_test_runner.py", line 340, in _run_reftest
    test_result = self._compare_output_with_reference(reference_output, test_output, reference_filename, expectation == '!=')
  File "/Volumes/Data/worker/iOS-15-Simulator-WK2-Tests-EWS/build/Tools/Scripts/webkitpy/layout_tests/controllers/single_test_runner.py", line 446, in _compare_output_with_reference
    diff_result.passed = self._test_passes_fuzzy_matching(fuzzy_tolerance, diff_result.fuzzy_data)
  File "/Volumes/Data/worker/iOS-15-Simulator-WK2-Tests-EWS/build/Tools/Scripts/webkitpy/layout_tests/controllers/single_test_runner.py", line 401, in _test_passes_fuzzy_matching
    actualMaxDifference = fuzzy_result['max_difference']
TypeError: 'NoneType' object is not subscriptable
10:08:28.673 681 Stopping HTTP server ...
10:08:28.929 681 Stopping WebSocket server ...
10:08:29.139 681 Stopping Web Platform Test server ...
program finished with exit code 254

and this means that the script fails to generate results.html, so the entire run is wasted.

[Radar WebKit Bug Importer]

<rdar://problem/92683094>

[Jonathan Bedard]

That doesn't look like a failure shutting down simulators, that's a failure in one of our child processes in Python code when retrying, this bit is probably the key:

EWS/build/Tools/Scripts/webkitpy/layout_tests/controllers/single_test_runner.py", line 401, in _test_passes_fuzzy_matching
    actualMaxDifference = fuzzy_result['max_difference']
TypeError: 'NoneType' object is not subscriptable

[Simon Fraser (smfr)]

Ah I missed that. I wonder why this just happens sometimes.