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Re: Etiquette about test regression, bug severities, etc.




Ian Jackson:
> Now that we have autopkgtests blocking testing migration, there is a
> much stronger incentive for people to keep their tests passing in
> testing.
> 

s/blocking/delaying/

While it is a goal to get it to a blocking state, we are not there yet.

> If one's tests are broken by an update to another package, and the
> increased britney migration delay doesn't do the job (perhaps the
> delay is too short, or there is a problem with the ci arrangements)
> then ideally there would be a bug open against the other package.
> That bug would stop the migration.
> 
> There are some problems with this, though:
> 
>  * The only available bug severity is `serious' which also triggers
>    testing autoremovals.  [...]

FTR: If you want to block testing migration, you can simply file the RC
bug against the unstable version of the package.  When the bug only
affects unstable, britney counts it as a regression and blocks testing
migration.  However, the auto-removal only considers bugs that affect
testing, so the bug is not going to trigger an auto-removal.

> 
> [...]
> IMO we need a bug severity or tag that has the following properties:
> 
> [...]

This seems like a lot of work to implement a self-help system that will
solve the interim/temporary phase where autopkgtests regressions are not
blocking testing migrations.

Cost-benefit-wise I think we are better off spending our resources
working on making the autopkgtest infrastructure and tests mature enough
that we can start to make the regressions blockers by default.

> 
> In the absence of such a self-help system, would it normally be
> appropriate to ask the release team to manually defer the migration ?
> If so then maybe that could be written down somewhere.  Also it should
> probably make clear that such a request should not occur routinely,
> only if either (i) the maintainers of the packages involved disagree
> or (ii) the matter is urgent (eg because the dependency package will
> migrate in the next day or two).
> 
> Thanks,
> Ian.
> 

For (i), I would start with:  Can we agree that after the upload, the
recent change:

"""
  makes the [reverse dependency] unusable or mostly so, or causes data
  loss, or introduces a security hole allowing access to the accounts of
  users who use the package?
"""[0]


If yes, then move the discussion to which package should be changed to
resolve the situation.  Note that if the reverse dependency is the one
that need changes to cope, then it often makes sense to file an RC bug
against *both* packages[1].


If you cannot agree on whether the reverse dependency is now so broken
that it warrants an RC bug in at least one of the two packages involved,
then the release team is officially the final arbiter for the RCness of
a bug.  At that point, the release team will effectively decide whether
the regression is severe enough that it should block testing migration
(preferably via RC bugs, but failing that we will deploy a block hint).


For (ii), a regression in the testing will cause a 10 day delay on top
of the regular urgency under normal circumstances and will eventually be
a migration blocker.
  If we need a standardized process for blocking uploads in this
situation, then it smells like we are doing something wrong (acting too
slow, or focusing on the wrong aspects, etc.).

Thanks,
~Niels

[0] I am using the definition for "grave" bugs here with minor
modification; I would avoid the "package maintainer's [...]
opinion"-clause for "serious" as it is ambiguous whose opinion counts in
this case.

[1] To ensure upgrade paths without breakage on the end user systems,
the package triggering the regression in the reverse dependency will
need a versioned Breaks (or a SONAME bump, etc.).  YMMV and alternatives
can include:

 1) removing the reverse dependency from testing, or
 2) reverting the upload of the package triggering the regression

if the issue is not resolved/resolvable in a timely fashion.