Re: [PATCH] t/Makefile: add a rule to re-run previously-failed tests

[Jeff King <peff@peff.net>]

On Wed, Jun 29, 2016 at 09:02:37AM +0200, Johannes Schindelin wrote:

> It is the most convenient way to determine which tests failed after
> running the entire test suite, in parallel, to look for left-over "trash
> directory.t*" subdirectories in the t/ subdirectory.

As Junio noted, this doesn't work with --root. I have sometimes used:

  grep 'failed [^0]' test-results/*

for this purpose.

> This patch automates the process of determinig which tests failed
> previously and re-running them; It turned out to be quite convenient
> when trying to squash bugs that crept in during rebases.

I suspect your response will be "perl tools on Windows are too painful
to use", but the "prove" tool which comes with perl can do this and more
(e.g., running the failed tests first, and then following up with the
others to double-check), and our test suite supports it quite well.

  $ grep -B1 PROVE config.mak
  # run tests in parallel, with slow ones first to keep pipelines full
  GIT_PROVE_OPTS = -j16 --state=slow,save

  $ cd t
  $ make prove
  ... reports some test failed ...
  $ prove --state=failed
  ... re-runs just the failed test ...

-Peff