[tor-bugs] #29585 [Core Tor/Tor]: Intermittent test failures in dir/dirserv_read_measured_bandwidths

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#29585: Intermittent test failures in dir/dirserv_read_measured_bandwidths
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 Reporter:  teor                          |          Owner:  (none)
     Type:  defect                        |         Status:  new
 Priority:  High                          |      Milestone:  Tor:
                                          |  unspecified
Component:  Core Tor/Tor                  |        Version:  Tor:
                                          |  unspecified
 Severity:  Normal                        |     Resolution:
 Keywords:  tor-ci, tor-test, tor-bwauth  |  Actual Points:
Parent ID:                                |         Points:  1
 Reviewer:                                |        Sponsor:
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Comment (by teor):

 Replying to [comment:6 juga]:
 > Replying to [comment:5 teor]:
 > > Unstable tests can fail, even if there are no changes to any code run
 by that test.
 >
 > what is an unstable test?

 A test that sometimes passes, and sometimes fails.

 > > Is there an obvious error in dirserv_read_measured_bandwidths that
 caused the failure?
 >
 > No, but let me try to explain what i see in case helps you to come out
 with an explanation.
 >
 > The test [0] that is failing is testing a bandwidth file with only the
 timestamp and a new line.
 > `dirserv_read_measured_bandwidths` should parse the timestamp correctly,
 assign `bw_file_headers` and return 0.
 >
 > It could return -1 instead of 0 in case:
 > - Can't open the bandwidth file
 > - The bandwidth file is empty

 There could have been a temporary file descriptor shortage, but that is
 unlikely.
 Permissions issues usually cause tests to fail all the time.

 > - The timestamp line doesn't end with new line
 > - The timestamp can't be parsed as integer

 File corruption is unlikely.

 > - The timestamp is old

 How old?

 > All of this is initialized in the test, and in theory, correctly. And if
 it's not, it should then fail all the times.

 What if the the time changed on the local system between tests?

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/29585#comment:7>
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