[tor-bugs] #29036 [Core Tor/Tor]: Coverage merge failures cause test_process_slow stderr check to fail

[Tor Bug Tracker & Wiki]

#29036: Coverage merge failures cause test_process_slow stderr check to fail
----------------------------+----------------------------------------------
     Reporter:  teor        |      Owner:  (none)
         Type:  defect      |     Status:  new
     Priority:  Medium      |  Milestone:  Tor: 0.4.1.x-final
    Component:  Core        |    Version:  Tor: unspecified
  Tor/Tor                   |
     Severity:  Critical    |   Keywords:  041-proposed, regression, tor-ci
Actual Points:              |  Parent ID:
       Points:  0.5         |   Reviewer:
      Sponsor:              |
----------------------------+----------------------------------------------
 When tor's coverage CI fails to merge coverage records, it logs to stderr.
 This causes the process stderr checks to fail.
 {{{
 slow/process/callbacks:
 profiling:/home/travis/build/teor2345/tor/src/trunnel
 /src_trunnel_libor_trunnel_testing_a-netinfo.gcda:Merge mismatch for
 function 47
   FAIL src/test/test_process_slow.c:241:
 assert(smartlist_len(process_data->stderr_data) OP_EQ 3): 4 vs 3
   [callbacks FAILED]
 }}}
 https://travis-ci.org/teor2345/tor/jobs/477561625#L5661

 We could skip this test when coverage is active?
 Or even better, we could allow 3 or 4 stderr lines when coverage is
 active?

 This is a critical bug, because it's a CI failure. But it doesn't fail all
 the time. Maybe we should turn off CI caching on coverage builds, or
 exclude coverage records from the CI cache?

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/29036>
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