tests: Infrastructure for Git smoke testing

tests: Infrastructure for Git smoke testing

Add the capability to send smoke reports from the Git test suite.

Currently we only notice bugs in the test suite when it's run
manually. Bugs in Git that only occur on obscure platforms or setups
that the core developers aren't using can thus go unnoticed.

This series aims to change that. With it, anyone that's interested in
avoiding bitrot in Git can volunteer to run a smoke tester. A smoke
tester periodically compiles the latest version of Git, runs the test
suite, and submits a report to a central server indicating how the
test run went.

A smoke tester might run something like this in cron:

    #!/bin/sh
    cd ~/g/git
    git fetch
    for branch in maint master next pu; do
        git checkout origin/$i &&
        make clean all &&
        cd t &&
        make smoke_report
    done

The smoker might want to compile git with non-default flags, include
bisecting functionality or run the tests under valgrind. Doing that is
outside the scope of this patch, this just adds a report submission
mechanism. But including a canonical smoke runner is something we'll
want to include eventually.

What this does now is add smoke and smoke_report targets to t/Makefile
(this example only uses a few tests for demonstration):

    $ make clean smoke
    rm -f -r 'trash directory'.* test-results
    rm -f t????/cvsroot/CVSROOT/?*
    rm -f -r valgrind/bin
    rm -f .prove
    perl ./harness --git-version="1.7.2.1.173.gc9b40" \
                    --no-verbose \
                    --archive="test-results/git-smoke.tar.gz" \
                    t0000-basic.sh t0001-init.sh t0002-gitfile.sh t0003-attributes.sh t0004-unwritable.sh t0005-signals.sh t0006-date.sh
    t0000-basic.sh ....... ok
    t0001-init.sh ........ ok
    t0002-gitfile.sh ..... ok
    t0003-attributes.sh .. ok
    t0004-unwritable.sh .. ok
    t0005-signals.sh ..... ok
    t0006-date.sh ........ ok
    All tests successful.

    Test Summary Report
    -------------------
    t0000-basic.sh     (Wstat: 0 Tests: 46 Failed: 0)
      TODO passed:   5
    Files=7, Tests=134,  3 wallclock secs ( 0.06 usr  0.05 sys +  0.23 cusr  1.33 csys =  1.67 CPU)
    Result: PASS

    TAP Archive created at /home/avar/g/git/t/test-results/git-smoke.tar.gz

The smoke target uses TAP::Harness::Archive to aggregate the test
results into a tarball. The tarball contains two things, the output of
every test file that was run, and a metadata file:

Tarball contents:

    $ tar xzvf git-smoke.tar.gz
    t0004-unwritable.sh
    t0001-init.sh
    t0002-gitfile.sh
    t0005-signals.sh
    t0000-basic.sh
    t0003-attributes.sh
    t0006-date.sh
    meta.yml

A test report:

    $ cat t0005-signals.sh
    ok 1 - sigchain works
    # passed all 1 test(s)
    1..1

A metadata file:

    ---
    extra_properties:
    file_attributes:
      -
        description: t0000-basic.sh
        end_time: 1280437324.61398
        start_time: 1280437324.22186
      -
        description: t0001-init.sh
        end_time: 1280437325.12346
        start_time: 1280437324.62393
      -
        description: t0002-gitfile.sh
        end_time: 1280437325.29428
        start_time: 1280437325.13646
      -
        description: t0003-attributes.sh
        end_time: 1280437325.59678
        start_time: 1280437325.30565
      -
        description: t0004-unwritable.sh
        end_time: 1280437325.77376
        start_time: 1280437325.61003
      -
        description: t0005-signals.sh
        end_time: 1280437325.85426
        start_time: 1280437325.78727
      -
        description: t0006-date.sh
        end_time: 1280437326.2362
        start_time: 1280437325.86768
    file_order:
      - t0000-basic.sh
      - t0001-init.sh
      - t0002-gitfile.sh
      - t0003-attributes.sh
      - t0004-unwritable.sh
      - t0005-signals.sh
      - t0006-date.sh
    start_time: 1280437324
    stop_time: 1280437326

The "extra_properties" hash is where we'll stick Git-specific info,
like whether Git was compiled with gettext or the fallback regex
engine, and what branch we're compiling. Currently no metadata like
this is included.

The entire tarball is then submitted to a central smokebox at
smoke.git.nix.is. This is done with curl(1) via the "smoke_report"
target:

    $ make smoke_report
    curl \
                    -H "Expect: " \
                    -F project=Git \
                    -F architecture=x86_64 \
                    -F platform=Linux \
                    -F revision="1.7.2.1.173.gc9b40" \
                    -F report_file=@test-results/git-smoke.tar.gz \
                    http://smoke.git.nix.is/app/projects/process_add_report/1 \
            | grep -v ^Redirecting
      % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                     Dload  Upload   Total   Spent    Left  Speed
    100  117k  100    63  100  117k      3   6430  0:00:21  0:00:18  0:00:03     0
    Reported #8 added.

Reports are then made available on the smokebox via a web interface:

    http://smoke.git.nix.is/app/projects/smoke_reports/1

The smoke reports are also mirrored to a Git repository hosted on
GitHub:

    http://github.com/gitsmoke/smoke-reports

The Smolder SQLite database that contains metadata about the reports
is also made available:

    http://github.com/gitsmoke/smoke-database

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>