It's easy to miss an "&&"-chain in a test script, like:
test_expect_success 'check something important' '
cmd1 &&
cmd2
cmd3
'
The test harness will notice if cmd3 fails, but a failure of
cmd1 or cmd2 will go unnoticed, as their exit status is lost
after cmd3 runs.
The toy example above is easy to spot because the "cmds" are
all the same length, but real code is much more complicated.
It's also difficult to detect these situations by statically
analyzing the shell code with regexps (like the
check-non-portable-shell script does); there's too much
context required to know whether a &&-chain is appropriate
on a given line or not.
This patch instead lets the shell check each test by
sticking a command with a specific and unusual return code
at the top of each test, like:
(exit 117) &&
cmd1 &&
cmd2
cmd3
In a well-formed test, the non-zero exit from the first
command prevents any of the rest from being run, and the
test's exit code is 117. In a bad test (like the one above),
the 117 is lost, and cmd3 is run.
When we encounter a failure of this check, we abort the test
script entirely. For one thing, we have no clue which subset
of the commands in the test snippet were actually run.
Running further tests would be pointless, because we're now
in an unknown state. And two, this is not a "test failure"
in the traditional sense. The test script is buggy, not the
code it is testing. We should be able to fix these problems
in the script once, and not have them come back later as a
regression in git's code.
After checking a test snippet for --chain-lint, we do still
run the test itself. We could actually have a pure-lint
mode which just checks each test, but there are a few
reasons not to. One, because the tests are executing
arbitrary code, which could impact the later environment
(e.g., that could impact which set of tests we run at all).
And two, because a pure-lint mode would still be expensive
to run, because a significant amount of code runs outside of
the test_expect_* blocks. Instead, this option is designed
to be used as part of a normal test suite run, where it adds
very little overhead.
Turning on this option detects quite a few problems in
existing tests, which will be fixed in subsequent patches.
However, there are a number of places it cannot reach:
- it cannot find a failure to break out of loops on error,
like:
cmd1 &&
for i in a b c; do
cmd2 $i
done &&
cmd3
which will not notice failures of "cmd2 a" or "cmd b"
- it cannot find a missing &&-chain inside a block or
subfunction, like:
foo () {
cmd1
cmd2
}
foo &&
bar
which will not notice a failure of cmd1.
- it only checks tests that you run; every platform will
have some tests skipped due to missing prequisites,
so it's impossible to say from one run that the test
suite is free of broken &&-chains. However, all tests get
run by _somebody_, so eventually we will notice problems.
- it does not operate on test_when_finished or prerequisite
blocks. It could, but these tends to be much shorter and
less of a problem, so I punted on them in this patch.
This patch was inspired by an earlier patch by Jonathan
Nieder:
http://article.gmane.org/gmane.comp.version-control.git/235913
This implementation and all bugs are mine.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
////////////////////////////////////////////////////////////////
Git - the stupid content tracker
////////////////////////////////////////////////////////////////
"git" can mean anything, 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
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.
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).
Many Git online resources are accessible from http://git-scm.com/
including full documentation and Git related tools.
The user discussion and development of Git take place on the Git
mailing list -- everyone is welcome to post bug reports, feature
requests, comments and patches to git@vger.kernel.org (read
Documentation/SubmittingPatches for instructions on patch submission).
To subscribe to the list, send an email with just "subscribe git" in
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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.
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