We always set the name and email for committer and author idents to make
the test suite more deterministic, but not timestamps. Many scripts use
test_tick to get consistent and sensibly incrementing timestamps as they
create commits. But other scripts don't particularly care about the
timestamp, and are happy to use whatever the current system time is.
This non-determinism can be annoying:
- when debugging a test, comparing results between two runs can be
difficult, because the commit ids change
- this can sometimes cause tests to be racy. E.g., traversal order
depends on timestamp order. Even in a well-ordered set of commands,
because our timestamp granularity is one second, two commits might
sometimes have the same timestamp and sometimes differ.
Let's set a default timestamp for all scripts to use. Any that use
test_tick already will be unaffected (because their first test_tick call
will overwrite our default), but it will make things a bit more
deterministic for those that don't.
We should be able to choose any time we want here. I picked this one
because:
- it differs from the initial test_tick default, which may make it
easier to distinguish when debugging tests. I picked "April 1st
13:14:15" in the hope that it might stand out.
- it's slightly before the test_tick default. Some tests create some
commits before the first call to test_tick, so using an older
timestamps for those makes sense chronologically. Note that this
isn't how things currently work (where system times are usually more
recent than test_tick), but that also allows us to flush out a few
hidden timestamp dependencies (like the one recently fixed in
t5539).
- we could likewise pick any timezone we want. Choosing +0000 would
have required fixing up fewer tests, but we're more likely to turn
up interesting cases by not matching $TZ exactly. And since
test_tick already checks "-0700", let's try something in the "+"
zone range for variety.
It's possible that the non-deterministic times could help flush out bugs
(e.g., if something broke when the clock flipped over to 2021, our test
suite would let us know). But historically that hasn't been the case;
all time-dependent outcomes we've seen turned out to be accidentally
flaky tests (which we fixed by using test_tick). If we do want to cover
handling the current time, we should dedicate one script to doing so,
and have it unset GIT_COMMITTER_DATE explicitly.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Git - fast, scalable, distributed revision control system
Git is a fast, scalable, distributed revision control system with an
unusually rich command set that provides both high-level operations
and full access to internals.
Git is an Open Source project covered by the GNU General Public
License version 2 (some parts of it are under different licenses,
compatible with the GPLv2). It was originally written by Linus
Torvalds with help of a group of hackers around the net.
Please read the file INSTALL for installation instructions.
Many Git online resources are accessible from https://git-scm.com/
including full documentation and Git related tools.
See Documentation/gittutorial.txt to get started, then see
Documentation/giteveryday.txt for a useful minimum set of commands, and
Documentation/git-<commandname>.txt for documentation of each command.
If git has been correctly installed, then the tutorial can also be
read with man gittutorial or git help tutorial, and the
documentation of each command with man git-<commandname> or git help <commandname>.
CVS users may also want to read Documentation/gitcvs-migration.txt
(man gitcvs-migration or git help cvs-migration if git is
installed).
Issues which are security relevant should be disclosed privately to
the Git Security mailing list git-security@googlegroups.com.
The maintainer frequently sends the "What's cooking" reports that
list the current status of various development topics to the mailing
list. The discussion following them give a good reference for
project status, development direction and remaining tasks.
The name "git" was given by Linus Torvalds when he wrote the very
first version. He described the tool as "the stupid content tracker"
and the name as (depending on your mood):
random three-letter combination that is pronounceable, and not
actually used by any common UNIX command. The fact that it is a
mispronunciation of "get" may or may not be relevant.
stupid. contemptible and despicable. simple. Take your pick from the
dictionary of slang.
"global information tracker": you're in a good mood, and it actually
works for you. Angels sing, and a light suddenly fills the room.
"goddamn idiotic truckload of sh*t": when it breaks
