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Ævar Arnfjörð Bjarmason 99d9050d25 t/README: Update "Skipping tests" to align with best practices 
The example I initially added to "Skipping tests" wasn't very
good. We'd rather skip tests using the three-arg prereq form to the
test_* functions, not bail out with a skip message.

Change the documentation to reflect that, but retain the bailout
example under a disclaimer which explains that it's probably not a
good idea to use it.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2010-08-18 12:42:45 -07:00

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Core GIT Tests
==============
This directory holds many test scripts for core GIT tools. The
first part of this short document describes how to run the tests
and read their output.
When fixing the tools or adding enhancements, you are strongly
encouraged to add tests in this directory to cover what you are
trying to fix or enhance. The later part of this short document
describes how your test scripts should be organized.
Running Tests
-------------
The easiest way to run tests is to say "make". This runs all
the tests.
*** t0000-basic.sh ***
ok 1 - .git/objects should be empty after git init in an empty repo.
ok 2 - .git/objects should have 3 subdirectories.
ok 3 - success is reported like this
...
ok 43 - very long name in the index handled sanely
# fixed 1 known breakage(s)
# still have 1 known breakage(s)
# passed all remaining 42 test(s)
1..43
*** t0001-init.sh ***
ok 1 - plain
ok 2 - plain with GIT_WORK_TREE
ok 3 - plain bare
Since the tests all output TAP (see http://testanything.org) they can
be run with any TAP harness. Here's an example of parallel testing
powered by a recent version of prove(1):
$ prove --timer --jobs 15 ./t[0-9]*.sh
[19:17:33] ./t0005-signals.sh ................................... ok 36 ms
[19:17:33] ./t0022-crlf-rename.sh ............................... ok 69 ms
[19:17:33] ./t0024-crlf-archive.sh .............................. ok 154 ms
[19:17:33] ./t0004-unwritable.sh ................................ ok 289 ms
[19:17:33] ./t0002-gitfile.sh ................................... ok 480 ms
===( 102;0 25/? 6/? 5/? 16/? 1/? 4/? 2/? 1/? 3/? 1... )===
prove and other harnesses come with a lot of useful options. The
--state option in particular is very useful:
# Repeat until no more failures
$ prove -j 15 --state=failed,save ./t[0-9]*.sh
You can also run each test individually from command line, like this:
$ sh ./t3010-ls-files-killed-modified.sh
ok 1 - git update-index --add to add various paths.
ok 2 - git ls-files -k to show killed files.
ok 3 - validate git ls-files -k output.
ok 4 - git ls-files -m to show modified files.
ok 5 - validate git ls-files -m output.
# passed all 5 test(s)
1..5
You can pass --verbose (or -v), --debug (or -d), and --immediate
(or -i) command line argument to the test, or by setting GIT_TEST_OPTS
appropriately before running "make".
--verbose::
This makes the test more verbose. Specifically, the
command being run and their output if any are also
output.
--debug::
This may help the person who is developing a new test.
It causes the command defined with test_debug to run.
--immediate::
This causes the test to immediately exit upon the first
failed test.
--long-tests::
This causes additional long-running tests to be run (where
available), for more exhaustive testing.
--valgrind::
Execute all Git binaries with valgrind and exit with status
126 on errors (just like regular tests, this will only stop
the test script when running under -i). Valgrind errors
go to stderr, so you might want to pass the -v option, too.
Since it makes no sense to run the tests with --valgrind and
not see any output, this option implies --verbose. For
convenience, it also implies --tee.
--tee::
In addition to printing the test output to the terminal,
write it to files named 't/test-results/$TEST_NAME.out'.
As the names depend on the tests' file names, it is safe to
run the tests with this option in parallel.
--with-dashes::
By default tests are run without dashed forms of
commands (like git-commit) in the PATH (it only uses
wrappers from ../bin-wrappers). Use this option to include
the build directory (..) in the PATH, which contains all
the dashed forms of commands. This option is currently
implied by other options like --valgrind and
GIT_TEST_INSTALLED.
--root=<directory>::
Create "trash" directories used to store all temporary data during
testing under <directory>, instead of the t/ directory.
Using this option with a RAM-based filesystem (such as tmpfs)
can massively speed up the test suite.
You can also set the GIT_TEST_INSTALLED environment variable to
the bindir of an existing git installation to test that installation.
You still need to have built this git sandbox, from which various
test-* support programs, templates, and perl libraries are used.
If your installed git is incomplete, it will silently test parts of
your built version instead.
When using GIT_TEST_INSTALLED, you can also set GIT_TEST_EXEC_PATH to
override the location of the dashed-form subcommands (what
GIT_EXEC_PATH would be used for during normal operation).
GIT_TEST_EXEC_PATH defaults to `$GIT_TEST_INSTALLED/git --exec-path`.
Skipping Tests
--------------
In some environments, certain tests have no way of succeeding
due to platform limitation, such as lack of 'unzip' program, or
filesystem that do not allow arbitrary sequence of non-NUL bytes
as pathnames.
You should be able to say something like
$ GIT_SKIP_TESTS=t9200.8 sh ./t9200-git-cvsexport-commit.sh
and even:
$ GIT_SKIP_TESTS='t[0-4]??? t91?? t9200.8' make
to omit such tests. The value of the environment variable is a
SP separated list of patterns that tells which tests to skip,
and either can match the "t[0-9]{4}" part to skip the whole
test, or t[0-9]{4} followed by ".$number" to say which
particular test to skip.
Note that some tests in the existing test suite rely on previous
test item, so you cannot arbitrarily disable one and expect the
remainder of test to check what the test originally was intended
to check.
Naming Tests
------------
The test files are named as:
tNNNN-commandname-details.sh
where N is a decimal digit.
First digit tells the family:
0 - the absolute basics and global stuff
1 - the basic commands concerning database
2 - the basic commands concerning the working tree
3 - the other basic commands (e.g. ls-files)
4 - the diff commands
5 - the pull and exporting commands
6 - the revision tree commands (even e.g. merge-base)
7 - the porcelainish commands concerning the working tree
8 - the porcelainish commands concerning forensics
9 - the git tools
Second digit tells the particular command we are testing.
Third digit (optionally) tells the particular switch or group of switches
we are testing.
If you create files under t/ directory (i.e. here) that is not
the top-level test script, never name the file to match the above
pattern. The Makefile here considers all such files as the
top-level test script and tries to run all of them. A care is
especially needed if you are creating a common test library
file, similar to test-lib.sh, because such a library file may
not be suitable for standalone execution.
Writing Tests
-------------
The test script is written as a shell script. It should start
with the standard "#!/bin/sh" with copyright notices, and an
assignment to variable 'test_description', like this:
#!/bin/sh
#
# Copyright (c) 2005 Junio C Hamano
#
test_description='xxx test (option --frotz)
This test registers the following structure in the cache
and tries to run git-ls-files with option --frotz.'
Source 'test-lib.sh'
--------------------
After assigning test_description, the test script should source
test-lib.sh like this:
. ./test-lib.sh
This test harness library does the following things:
- If the script is invoked with command line argument --help
(or -h), it shows the test_description and exits.
- Creates an empty test directory with an empty .git/objects database
and chdir(2) into it. This directory is 't/trash
directory.$test_name_without_dotsh', with t/ subject to change by
the --root option documented above.
- Defines standard test helper functions for your scripts to
use. These functions are designed to make all scripts behave
consistently when command line arguments --verbose (or -v),
--debug (or -d), and --immediate (or -i) is given.
Do's, don'ts & things to keep in mind
-------------------------------------
Here are a few examples of things you probably should and shouldn't do
when writing tests.
Do:
- Put all code inside test_expect_success and other assertions.
Even code that isn't a test per se, but merely some setup code
should be inside a test assertion.
- Chain your test assertions
Write test code like this:
git merge foo &&
git push bar &&
test ...
Instead of:
git merge hla
git push gh
test ...
That way all of the commands in your tests will succeed or fail. If
you must ignore the return value of something (e.g., the return
after unsetting a variable that was already unset is unportable) it's
best to indicate so explicitly with a semicolon:
unset HLAGH;
git merge hla &&
git push gh &&
test ...
- Check the test coverage for your tests. See the "Test coverage"
below.
Don't blindly follow test coverage metrics, they're a good way to
spot if you've missed something. If a new function you added
doesn't have any coverage you're probably doing something wrong,
but having 100% coverage doesn't necessarily mean that you tested
everything.
Tests that are likely to smoke out future regressions are better
than tests that just inflate the coverage metrics.
Don't:
- exit() within a <script> part.
The harness will catch this as a programming error of the test.
Use test_done instead if you need to stop the tests early (see
"Skipping tests" below).
- Break the TAP output
The raw output from your test may be interpreted by a TAP harness. TAP
harnesses will ignore everything they don't know about, but don't step
on their toes in these areas:
- Don't print lines like "$x..$y" where $x and $y are integers.
- Don't print lines that begin with "ok" or "not ok".
TAP harnesses expect a line that begins with either "ok" and "not
ok" to signal a test passed or failed (and our harness already
produces such lines), so your script shouldn't emit such lines to
their output.
You can glean some further possible issues from the TAP grammar
(see http://search.cpan.org/perldoc?TAP::Parser::Grammar#TAP_Grammar)
but the best indication is to just run the tests with prove(1),
it'll complain if anything is amiss.
Keep in mind:
- Inside <script> part, the standard output and standard error
streams are discarded, and the test harness only reports "ok" or
"not ok" to the end user running the tests. Under --verbose, they
are shown to help debugging the tests.
Skipping tests
--------------
If you need to skip tests you should do so be using the three-arg form
of the test_* functions (see the "Test harness library" section
below), e.g.:
test_expect_success PERL 'I need Perl' "
'$PERL_PATH' -e 'hlagh() if unf_unf()'
"
The advantage of skipping tests like this is that platforms that don't
have the PERL and other optional dependencies get an indication of how
many tests they're missing.
If the test code is too hairy for that (i.e. does a lot of setup work
outside test assertions) you can also skip all remaining tests by
setting skip_all and immediately call test_done:
if ! test_have_prereq PERL
then
skip_all='skipping perl interface tests, perl not available'
test_done
fi
The string you give to skip_all will be used as an explanation for why
the test was skipped.
End with test_done
------------------
Your script will be a sequence of tests, using helper functions
from the test harness library. At the end of the script, call
'test_done'.
Test harness library
--------------------
There are a handful helper functions defined in the test harness
library for your script to use.
- test_expect_success [<prereq>] <message> <script>
Usually takes two strings as parameter, and evaluates the
<script>. If it yields success, test is considered
successful. <message> should state what it is testing.
Example:
test_expect_success \
'git-write-tree should be able to write an empty tree.' \
'tree=$(git-write-tree)'
If you supply three parameters the first will be taken to be a
prerequisite, see the test_set_prereq and test_have_prereq
documentation below:
test_expect_success TTY 'git --paginate rev-list uses a pager' \
' ... '
You can also supply a comma-separated list of prerequisites, in the
rare case where your test depends on more than one:
test_expect_success PERL,PYTHON 'yo dawg' \
' test $(perl -E 'print eval "1 +" . qx[python -c "print 2"]') == "4" '
- test_expect_failure [<prereq>] <message> <script>
This is NOT the opposite of test_expect_success, but is used
to mark a test that demonstrates a known breakage. Unlike
the usual test_expect_success tests, which say "ok" on
success and "FAIL" on failure, this will say "FIXED" on
success and "still broken" on failure. Failures from these
tests won't cause -i (immediate) to stop.
Like test_expect_success this function can optionally use a three
argument invocation with a prerequisite as the first argument.
- test_expect_code [<prereq>] <code> <message> <script>
Analogous to test_expect_success, but pass the test if it exits
with a given exit <code>
test_expect_code 1 'Merge with d/f conflicts' 'git merge "merge msg" B master'
- test_debug <script>
This takes a single argument, <script>, and evaluates it only
when the test script is started with --debug command line
argument. This is primarily meant for use during the
development of a new test script.
- test_done
Your test script must have test_done at the end. Its purpose
is to summarize successes and failures in the test script and
exit with an appropriate error code.
- test_tick
Make commit and tag names consistent by setting the author and
committer times to defined stated. Subsequent calls will
advance the times by a fixed amount.
- test_commit <message> [<filename> [<contents>]]
Creates a commit with the given message, committing the given
file with the given contents (default for both is to reuse the
message string), and adds a tag (again reusing the message
string as name). Calls test_tick to make the SHA-1s
reproducible.
- test_merge <message> <commit-or-tag>
Merges the given rev using the given message. Like test_commit,
creates a tag and calls test_tick before committing.
- test_set_prereq SOME_PREREQ
Set a test prerequisite to be used later with test_have_prereq. The
test-lib will set some prerequisites for you, see the
"Prerequisites" section below for a full list of these.
Others you can set yourself and use later with either
test_have_prereq directly, or the three argument invocation of
test_expect_success and test_expect_failure.
- test_have_prereq SOME PREREQ
Check if we have a prerequisite previously set with
test_set_prereq. The most common use of this directly is to skip
all the tests if we don't have some essential prerequisite:
if ! test_have_prereq PERL
then
skip_all='skipping perl interface tests, perl not available'
test_done
fi
- test_external [<prereq>] <message> <external> <script>
Execute a <script> with an <external> interpreter (like perl). This
was added for tests like t9700-perl-git.sh which do most of their
work in an external test script.
test_external \
'GitwebCache::*FileCache*' \
"$PERL_PATH" "$TEST_DIRECTORY"/t9503/test_cache_interface.pl
If the test is outputting its own TAP you should set the
test_external_has_tap variable somewhere before calling the first
test_external* function. See t9700-perl-git.sh for an example.
# The external test will outputs its own plan
test_external_has_tap=1
- test_external_without_stderr [<prereq>] <message> <external> <script>
Like test_external but fail if there's any output on stderr,
instead of checking the exit code.
test_external_without_stderr \
'Perl API' \
"$PERL_PATH" "$TEST_DIRECTORY"/t9700/test.pl
- test_must_fail <git-command>
Run a git command and ensure it fails in a controlled way. Use
this instead of "! <git-command>". When git-command dies due to a
segfault, test_must_fail diagnoses it as an error; "! <git-command>"
treats it as just another expected failure, which would let such a
bug go unnoticed.
- test_might_fail <git-command>
Similar to test_must_fail, but tolerate success, too. Use this
instead of "<git-command> || :" to catch failures due to segv.
- test_cmp <expected> <actual>
Check whether the content of the <actual> file matches the
<expected> file. This behaves like "cmp" but produces more
helpful output when the test is run with "-v" option.
- test_when_finished <script>
Prepend <script> to a list of commands to run to clean up
at the end of the current test. If some clean-up command
fails, the test will not pass.
Example:
test_expect_success 'branch pointing to non-commit' '
git rev-parse HEAD^{tree} >.git/refs/heads/invalid &&
test_when_finished "git update-ref -d refs/heads/invalid" &&
...
'
Prerequisites
-------------
These are the prerequisites that the test library predefines with
test_have_prereq.
See the prereq argument to the test_* functions in the "Test harness
library" section above and the "test_have_prereq" function for how to
use these, and "test_set_prereq" for how to define your own.
- PERL & PYTHON
Git wasn't compiled with NO_PERL=YesPlease or
NO_PYTHON=YesPlease. Wrap any tests that need Perl or Python in
these.
- POSIXPERM
The filesystem supports POSIX style permission bits.
- BSLASHPSPEC
Backslashes in pathspec are not directory separators. This is not
set on Windows. See 6fd1106a for details.
- EXECKEEPSPID
The process retains the same pid across exec(2). See fb9a2bea for
details.
- SYMLINKS
The filesystem we're on supports symbolic links. E.g. a FAT
filesystem doesn't support these. See 704a3143 for details.
- SANITY
Test is not run by root user, and an attempt to write to an
unwritable file is expected to fail correctly.
Tips for Writing Tests
----------------------
As with any programming projects, existing programs are the best
source of the information. However, do _not_ emulate
t0000-basic.sh when writing your tests. The test is special in
that it tries to validate the very core of GIT. For example, it
knows that there will be 256 subdirectories under .git/objects/,
and it knows that the object ID of an empty tree is a certain
40-byte string. This is deliberately done so in t0000-basic.sh
because the things the very basic core test tries to achieve is
to serve as a basis for people who are changing the GIT internal
drastically. For these people, after making certain changes,
not seeing failures from the basic test _is_ a failure. And
such drastic changes to the core GIT that even changes these
otherwise supposedly stable object IDs should be accompanied by
an update to t0000-basic.sh.
However, other tests that simply rely on basic parts of the core
GIT working properly should not have that level of intimate
knowledge of the core GIT internals. If all the test scripts
hardcoded the object IDs like t0000-basic.sh does, that defeats
the purpose of t0000-basic.sh, which is to isolate that level of
validation in one place. Your test also ends up needing
updating when such a change to the internal happens, so do _not_
do it and leave the low level of validation to t0000-basic.sh.
Test coverage
-------------
You can use the coverage tests to find code paths that are not being
used or properly exercised yet.
To do that, run the coverage target at the top-level (not in the t/
directory):
make coverage
That'll compile Git with GCC's coverage arguments, and generate a test
report with gcov after the tests finish. Running the coverage tests
can take a while, since running the tests in parallel is incompatible
with GCC's coverage mode.
After the tests have run you can generate a list of untested
functions:
make coverage-untested-functions
You can also generate a detailed per-file HTML report using the
Devel::Cover module. To install it do:
# On Debian or Ubuntu:
sudo aptitude install libdevel-cover-perl
# From the CPAN with cpanminus
curl -L http://cpanmin.us | perl - --sudo --self-upgrade
cpanm --sudo Devel::Cover
Then, at the top-level:
make cover_db_html
That'll generate a detailed cover report in the "cover_db_html"
directory, which you can then copy to a webserver, or inspect locally
in a browser.
Smoke testing
-------------
The Git test suite has support for smoke testing. Smoke testing is
when you submit the results of a test run to a central server for
analysis and aggregation.
Running a smoke tester is an easy and valuable way of contributing to
Git development, particularly if you have access to an uncommon OS on
obscure hardware.
After building Git you can generate a smoke report like this in the
"t" directory:
make clean smoke
You can also pass arguments via the environment. This should make it
faster:
GIT_TEST_OPTS='--root=/dev/shm' TEST_JOBS=10 make clean smoke
The "smoke" target will run the Git test suite with Perl's
"TAP::Harness" module, and package up the results in a .tar.gz archive
with "TAP::Harness::Archive". The former is included with Perl v5.10.1
or later, but you'll need to install the latter from the CPAN. See the
"Test coverage" section above for how you might do that.
Once the "smoke" target finishes you'll see a message like this:
TAP Archive created at <path to git>/t/test-results/git-smoke.tar.gz
To upload the smoke report you need to have curl(1) installed, then
do:
make smoke_report
To upload the report anonymously. Hopefully that'll return something
like "Reported #7 added.".
If you're going to be uploading reports frequently please request a
user account by E-Mailing gitsmoke@v.nix.is. Once you have a username
and password you'll be able to do:
SMOKE_USERNAME=<username> SMOKE_PASSWORD=<password> make smoke_report
You can also add an additional comment to attach to the report, and/or
a comma separated list of tags:
SMOKE_USERNAME=<username> SMOKE_PASSWORD=<password> \
SMOKE_COMMENT=<comment> SMOKE_TAGS=<tags> \
make smoke_report
Once the report is uploaded it'll be made available at
http://smoke.git.nix.is, here's an overview of Recent Smoke Reports
for Git:
http://smoke.git.nix.is/app/projects/smoke_reports/1
The reports will also be mirrored to GitHub every few hours:
http://github.com/gitsmoke/smoke-reports
The Smolder SQLite database is also mirrored and made available for
download:
http://github.com/gitsmoke/smoke-database
Note that the database includes hashed (with crypt()) user passwords
and E-Mail addresses. Don't use a valuable password for the smoke
service if you have an account, or an E-Mail address you don't want to
be publicly known. The user accounts are just meant to be convenient
labels, they're not meant to be secure.
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