git
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
t/Makefile defines a target for each test file, such that you can also use shell pattern matching to run a subset of the tests:
make *checkout*
will run all tests with 'checkout' in their filename.
Since the tests all output TAP (see https://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 give DEFAULT_TEST_TARGET=prove on the make command (or define it in config.mak) to cause "make test" to run tests under prove. GIT_PROVE_OPTS can be used to pass additional options, e.g.
$ make DEFAULT_TEST_TARGET=prove GIT_PROVE_OPTS='--timer --jobs 16' test
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". Short options can be bundled, i.e. '-d -v' is the same as '-dv'.
-v:: --verbose:: This makes the test more verbose. Specifically, the command being run and their output if any are also output.
--verbose-only=:: Like --verbose, but the effect is limited to tests with numbers matching . The number matched against is simply the running count of the test within the file.
-x::
Turn on shell tracing (i.e., set -x) during the tests
themselves. Implies --verbose.
Ignored in test scripts that set the variable 'test_untraceable'
to a non-empty value, unless it's run with a Bash version
supporting BASH_XTRACEFD, i.e. v4.1 or later.
-d:: --debug:: This may help the person who is developing a new test. It causes the command defined with test_debug to run. The "trash" directory (used to store all temporary data during testing) is not deleted even if there are no failed tests so that you can inspect its contents after the test finished.
-i:: --immediate:: This causes the test to immediately exit upon the first failed test. Cleanup commands requested with test_when_finished are not executed if the test failed, in order to keep the state for inspection by the tester to diagnose the bug.
-l:: --long-tests:: This causes additional long-running tests to be run (where available), for more exhaustive testing.
-r:: --run=:: Run only the subset of tests indicated by . See section "Skipping Tests" below for syntax.
--valgrind=:: Execute all Git binaries under valgrind tool and exit with status 126 on errors (just like regular tests, this will only stop the test script when running under -i).
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.
<tool> defaults to 'memcheck', just like valgrind itself.
Other particularly useful choices include 'helgrind' and
'drd', but you may use any tool recognized by your valgrind
installation.
As a special case, <tool> can be 'memcheck-fast', which uses
memcheck but disables --track-origins. Use this if you are
running tests in bulk, to see if there are _any_ memory
issues.
Note that memcheck is run with the option --leak-check=no,
as the git process is short-lived and some errors are not
interesting. In order to run a single command under the same
conditions manually, you should set GIT_VALGRIND to point to
the 't/valgrind/' directory and use the commands under
't/valgrind/bin/'.
--valgrind-only=:: Like --valgrind, but the effect is limited to tests with numbers matching . The number matched against is simply the running count of the test within the file.
--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.
-V::
--verbose-log::
Write verbose output to the same logfile as --tee, but do
not write it to stdout. Unlike --tee --verbose, this option
is safe to use when stdout is being consumed by a TAP parser
like prove. Implies --tee and --verbose.
--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.
--no-bin-wrappers::
By default, the test suite uses the wrappers in
../bin-wrappers/ to execute git and friends. With this option,
../git and friends are run directly. This is not recommended
in general, as the wrappers contain safeguards to ensure that no
files from an installed Git are used, but can speed up test runs
especially on platforms where running shell scripts is expensive
(most notably, Windows).
--root=:: Create "trash" directories used to store all temporary data during testing under , instead of the t/ directory. Using this option with a RAM-based filesystem (such as tmpfs) can massively speed up the test suite.
--chain-lint:: --no-chain-lint:: If --chain-lint is enabled, the test harness will check each test to make sure that it properly "&&-chains" all commands (so that a failure in the middle does not go unnoticed by the final exit code of the test). This check is performed in addition to running the tests themselves. You may also enable or disable this feature by setting the GIT_TEST_CHAIN_LINT environment variable to "1" or "0", respectively.
--stress::
Run the test script repeatedly in multiple parallel jobs until
one of them fails. Useful for reproducing rare failures in
flaky tests. The number of parallel jobs is, in order of
precedence: the value of the GIT_TEST_STRESS_LOAD
environment variable, or twice the number of available
processors (as shown by the 'getconf' utility), or 8.
Implies --verbose -x --immediate to get the most information
about the failure. Note that the verbose output of each test
job is saved to 't/test-results/$TEST_NAME.stress-.out',
and only the output of the failed test job is shown on the
terminal. The names of the trash directories get a
'.stress-' suffix, and the trash directory of the failed
test job is renamed to end with a '.stress-failed' suffix.
--stress-jobs=::
Override the number of parallel jobs. Implies --stress.
--stress-limit=::
When combined with --stress run the test script repeatedly
this many times in each of the parallel jobs or until one of
them fails, whichever comes first. Implies --stress.
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.
For an individual test suite --run could be used to specify that only some tests should be run or that some tests should be excluded from a run.
The argument for --run, , is a list of description substrings or globs or individual test numbers or ranges with an optional negation prefix (of '!') that define what tests in a test suite to include (or exclude, if negated) in the run. A range is two numbers separated with a dash and specifies an inclusive range of tests to run. You may omit the first or the second number to mean "from the first test" or "up to the very last test" respectively.
The argument to --run is split on commas into separate strings, numbers, and ranges, and picks all tests that match any of the individual selection criteria. If the substring of the description text that you want to match includes a comma, use the glob character '?' instead. For example --run='rebase,merge?cherry-pick' would match on all tests that match either the glob rebase or the glob merge?cherry-pick.
If --run starts with an unprefixed number or range, the initial set of tests to run is empty. If the first item starts with '!', all the tests are added to the initial set. After initial set is determined, every test number or range is added or excluded from the set one by one, from left to right.
For example, to run only tests up to a specific test (21), one could do this:
$ sh ./t9200-git-cvsexport-commit.sh --run='1-21'
or this:
$ sh ./t9200-git-cvsexport-commit.sh --run='-21'
Common case is to run several setup tests (1, 2, 3) and then a specific test (21) that relies on that setup:
$ sh ./t9200-git-cvsexport-commit.sh --run='1,2,3,21'
or:
$ sh ./t9200-git-cvsexport-commit.sh --run=1,2,3,21
or:
$ sh ./t9200-git-cvsexport-commit.sh --run='-3,21'
As noted above, the test set is built by going through the items from left to right, so this:
$ sh ./t9200-git-cvsexport-commit.sh --run='1-4,!3'
will run tests 1, 2, and 4. Items that come later have higher precedence. It means that this:
$ sh ./t9200-git-cvsexport-commit.sh --run='!3,1-4'
would just run tests from 1 to 4, including 3.
You may use negation with ranges. The following will run all test in the test suite except from 7 up to 11:
$ sh ./t9200-git-cvsexport-commit.sh --run='!7-11'
Sometimes there may be multiple tests with e.g. "setup" in their name that are needed and rather than figuring out the number for all of them we can just use "setup" as a substring/glob to match against the test description:
$ sh ./t0050-filesystem.sh --run=setup,9-11
or one could select both the setup tests and the rename ones (assuming all relevant tests had those words in their descriptions):
$ sh ./t0050-filesystem.sh --run=setup,rename
Some tests in a test suite rely on the previous tests performing certain actions, specifically some tests are designated as "setup" test, so you cannot arbitrarily disable one test and expect the rest to function correctly.
--run is mostly useful when you want to focus on a specific test and know what setup is needed for it. Or when you want to run everything up to a certain test.
Running tests with special setups
The whole test suite could be run to test some special features that cannot be easily covered by a few specific test cases. These could be enabled by running the test suite with correct GIT_TEST_ environment set.
GIT_TEST_FAIL_PREREQS= fails all prerequisites. This is useful for discovering issues with the tests where say a later test implicitly depends on an optional earlier test.
There's a "FAIL_PREREQS" prerequisite that can be used to test for whether this mode is active, and e.g. skip some tests that are hard to refactor to deal with it. The "SYMLINKS" prerequisite is currently excluded as so much relies on it, but this might change in the future.
GIT_TEST_SPLIT_INDEX= forces split-index mode on the whole test suite. Accept any boolean values that are accepted by git-config.
GIT_TEST_PASSING_SANITIZE_LEAK=true skips those tests that haven't declared themselves as leak-free by setting "TEST_PASSES_SANITIZE_LEAK=true" before sourcing "test-lib.sh". This test mode is used by the "linux-leaks" CI target.
GIT_TEST_PASSING_SANITIZE_LEAK=check checks that our "TEST_PASSES_SANITIZE_LEAK=true" markings are current. Rather than skipping those tests that haven't set "TEST_PASSES_SANITIZE_LEAK=true" before sourcing "test-lib.sh" this mode runs them with "--invert-exit-code". This is used to check that there's a one-to-one mapping between "TEST_PASSES_SANITIZE_LEAK=true" and those tests that pass under "SANITIZE=leak". This is especially useful when testing a series that fixes various memory leaks with "git rebase -x".
GIT_TEST_PASSING_SANITIZE_LEAK=check when combined with "--immediate" will run to completion faster, and result in the same failing tests.
GIT_TEST_PROTOCOL_VERSION=, when set, makes 'protocol.version' default to n.
GIT_TEST_FULL_IN_PACK_ARRAY= exercises the uncommon pack-objects code path where there are more than 1024 packs even if the actual number of packs in repository is below this limit. Accept any boolean values that are accepted by git-config.
GIT_TEST_OE_SIZE= exercises the uncommon pack-objects code path where we do not cache object size in memory and read it from existing packs on demand. This normally only happens when the object size is over 2GB. This variable forces the code path on any object larger than bytes.
GIT_TEST_OE_DELTA_SIZE= exercises the uncommon pack-objects code path where deltas larger than this limit require extra memory allocation for bookkeeping.
GIT_TEST_VALIDATE_INDEX_CACHE_ENTRIES= checks that cache-tree records are valid when the index is written out or after a merge. This is mostly to catch missing invalidation. Default is true.
GIT_TEST_COMMIT_GRAPH=, when true, forces the commit-graph to be written after every 'git commit' command, and overrides the 'core.commitGraph' setting to true.
GIT_TEST_COMMIT_GRAPH_CHANGED_PATHS=, when true, forces
commit-graph write to compute and write changed path Bloom filters for
every 'git commit-graph write', as if the --changed-paths option was
passed in.
GIT_TEST_FSMONITOR=$PWD/t7519/fsmonitor-all exercises the fsmonitor code paths for utilizing a (hook based) file system monitor to speed up detecting new or changed files.
GIT_TEST_INDEX_VERSION= exercises the index read/write code path for the index version specified. Can be set to any valid version (currently 2, 3, or 4).
GIT_TEST_PACK_USE_BITMAP_BOUNDARY_TRAVERSAL= if enabled will
use the boundary-based bitmap traversal algorithm. See the documentation
of pack.useBitmapBoundaryTraversal for more details.
GIT_TEST_PACK_SPARSE= if disabled will default the pack-objects builtin to use the non-sparse object walk. This can still be overridden by the --sparse command-line argument.
GIT_TEST_PRELOAD_INDEX= exercises the preload-index code path by overriding the minimum number of cache entries required per thread.
GIT_TEST_INDEX_THREADS= enables exercising the multi-threaded loading of the index for the whole test suite by bypassing the default number of cache entries and thread minimums. Setting this to 1 will make the index loading single threaded.
GIT_TEST_MULTI_PACK_INDEX=, when true, forces the multi-pack- index to be written after every 'git repack' command, and overrides the 'core.multiPackIndex' setting to true.
GIT_TEST_MULTI_PACK_INDEX_WRITE_INCREMENTAL=, when true, sets the '--incremental' option on all invocations of 'git multi-pack-index write'.
GIT_TEST_SIDEBAND_ALL=, when true, overrides the 'uploadpack.allowSidebandAll' setting to true, and when false, forces fetch-pack to not request sideband-all (even if the server advertises sideband-all).
GIT_TEST_DISALLOW_ABBREVIATED_OPTIONS=, when true (which is the default when running tests), errors out when an abbreviated option is used.
GIT_TEST_DEFAULT_HASH= specifies which hash algorithm to use in the test scripts. Recognized values for are "sha1" and "sha256".
GIT_TEST_DEFAULT_REF_FORMAT= specifies which ref storage format to use in the test scripts. Recognized values for are "files".
GIT_TEST_NO_WRITE_REV_INDEX=, when true disables the 'pack.writeReverseIndex' setting.
GIT_TEST_SPARSE_INDEX=, when true enables index writes to use the sparse-index format by default.
GIT_TEST_CHECKOUT_WORKERS= overrides the 'checkout.workers' setting to and 'checkout.thresholdForParallelism' to 0, forcing the execution of the parallel-checkout code.
GIT_TEST_FATAL_REGISTER_SUBMODULE_ODB=, when true, makes registering submodule ODBs as alternates a fatal action. Support for this environment variable can be removed once the migration to explicitly providing repositories when accessing submodule objects is complete or needs to be abandoned for whatever reason (in which case the migrated codepaths still retain their performance benefits).
GIT_TEST_REQUIRE_PREREQ= allows specifying a space separated list of prereqs that are required to succeed. If a prereq in this list is triggered by a test and then fails then the whole test run will abort. This can help to make sure the expected tests are executed and not silently skipped when their dependency breaks or is simply not present in a new environment.
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. 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", and an assignment to variable 'test_description', like this:
#!/bin/sh
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, and a '.stress-' suffix appended by the --stress option.
-
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.
Recommended style
-
Keep the test_expect_* function call and test title on the same line.
For example, with test_expect_success, write it like:
test_expect_success 'test title' ' ... test body ... '
Instead of:
test_expect_success
'test title'
'... test body ...'
-
End the line with an opening single quote.
-
Indent here-document bodies, and use "<<-" instead of "<<" to strip leading TABs used for indentation:
test_expect_success 'test something' ' cat >expect <<-\EOF && one two three EOF test_something > actual && test_cmp expect actual '
Instead of:
test_expect_success 'test something' ' cat >expect <<\EOF && one two three EOF test_something > actual && test_cmp expect actual '
- Quote or escape the EOF delimiter that begins a here-document if there is no parameter or other expansion in it, to signal readers that they can skim it more casually:
cmd <<-\EOF literal here-document text without any expansion EOF
Do's & don'ts
Here are a few examples of things you probably should and shouldn't do when writing tests.
The "do's:"
-
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, consider using a helper function (e.g. use sane_unset instead of unset, in order to avoid unportable return value for unsetting a variable that was already unset), or prepending the command with test_might_fail or test_must_fail.
-
Check the test coverage for your tests. See the "Test coverage" below.
Don't blindly follow test coverage metrics; if a new function you added doesn't have any coverage, then 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.
-
When a test checks for an absolute path that a git command generated, construct the expected value using $(pwd) rather than $PWD, $TEST_DIRECTORY, or $TRASH_DIRECTORY. It makes a difference on Windows, where the shell (MSYS bash) mangles absolute path names. For details, see the commit message of 4114156ae9.
-
Remember that inside the
-
Be careful when you loop
You may need to verify multiple things in a loop, but the following does not work correctly:
test_expect_success 'test three things' ' for i in one two three do test_something "$i" done && test_something_else '
Because the status of the loop itself is the exit status of the test_something in the last round, the loop does not fail when "test_something" for "one" or "two" fails. This is not what you want.
Instead, you can break out of the loop immediately when you see a failure. Because all test_expect_* snippets are executed inside a function, "return 1" can be used to fail the test immediately upon a failure:
test_expect_success 'test three things' ' for i in one two three do test_something "$i" || return 1 done && test_something_else '
Note that we still &&-chain the loop to propagate failures from earlier commands.
-
Repeat tests with slightly different arguments in a loop.
In some cases it may make sense to re-run the same set of tests with different options or commands to ensure that the command behaves despite the different parameters. This can be achieved by looping around a specific parameter:
for arg in '' "--foo" do test_expect_success "test command ${arg:-without arguments}" ' command $arg ' done
Note that while the test title uses double quotes ("), the test body should continue to use single quotes (') to avoid breakage in case the values contain e.g. quoting characters. The loop variable will be accessible regardless of the single quotes as the test body is passed to
eval.
And here are the "don'ts:"
-
Don't exit() within a
The harness will catch this as a programming error of the test. Use test_done instead if you need to stop the tests early (see "Skipping tests" below).
-
Don't use '! git cmd' when you want to make sure the git command exits with failure in a controlled way by calling "die()". Instead, use 'test_must_fail git cmd'. This will signal a failure if git dies in an unexpected way (e.g. segfault).
On the other hand, don't use test_must_fail for running regular platform commands; just use '! cmd'. We are not in the business of verifying that the world given to us sanely works.
-
Don't feed the output of a git command to a pipe, as in:
git -C repo ls-files | xargs -n 1 basename | grep foo
which will discard git's exit code and may mask a crash. In the above example, all exit codes are ignored except grep's.
Instead, write the output of that command to a temporary file with ">" or assign it to a variable with "x=$(git ...)" rather than pipe it.
-
Don't use command substitution in a way that discards git's exit code. When assigning to a variable, the exit code is not discarded, e.g.:
x=$(git cat-file -p $sha) && ...
is OK because a crash in "git cat-file" will cause the "&&" chain to fail, but:
test "refs/heads/foo" = "$(git symbolic-ref HEAD)"
is not OK and a crash in git could go undetected.
-
Don't use perl without spelling it as "$PERL_PATH". This is to help our friends on Windows where the platform Perl often adds CR before the end of line, and they bundle Git with a version of Perl that does not do so, whose path is specified with $PERL_PATH. Note that we provide a "perl" function which uses $PERL_PATH under the hood, so you do not need to worry when simply running perl in the test scripts (but you do, for example, on a shebang line or in a sub script created via "write_script").
-
Don't use sh without spelling it as "$SHELL_PATH", when the script can be misinterpreted by broken platform shell (e.g. Solaris).
-
Don't chdir around in tests. It is not sufficient to chdir to somewhere and then chdir back to the original location later in the test, as any intermediate step can fail and abort the test, causing the next test to start in an unexpected directory. Do so inside a subshell if necessary.
-
Don't save and verify the standard error of compound commands, i.e. group commands, subshells, and shell functions (except test helper functions like 'test_must_fail') like this:
( cd dir && git cmd ) 2>error && test_cmp expect error
When running the test with '-x' tracing, then the trace of commands executed in the compound command will be included in standard error as well, quite possibly throwing off the subsequent checks examining the output. Instead, save only the relevant git command's standard error:
( cd dir && git cmd 2>../error ) && test_cmp expect error
-
Don't 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 https://metacpan.org/pod/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.
-
Skipping tests
If you need to skip tests you should do so by 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 -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. Some of them are listed below; see test-lib-functions.sh for the full list and their options.
-
test_expect_success []
Usually takes two strings as parameters, and evaluates the
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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.
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test_debug
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.
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debug [options]
Run a git command inside a debugger. This is primarily meant for use when debugging a failing test script. With '-t', use your original TERM instead of test-lib.sh's "dumb", so that your debugger interface has colors.
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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.
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test_tick
Make commit and tag names consistent by setting the author and committer times to defined state. Subsequent calls will advance the times by a fixed amount.
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test_commit [ []]
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.
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test_merge
Merges the given rev using the given message. Like test_commit, creates a tag and calls test_tick before committing.
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test_set_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.
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test_have_prereq
Check if we have a prerequisite previously set with test_set_prereq. The most common way to use this explicitly (as opposed to the implicit use when an argument is passed to test_expect_*) is to skip all the tests at the start of the test script 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
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test_expect_code
Run a command and ensure that it exits with the given exit code. For example:
test_expect_success 'Merge with d/f conflicts' ' test_expect_code 1 git merge "merge msg" B master '
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test_must_fail []
Run a git command and ensure it fails in a controlled way. Use this instead of "! ". When git-command dies due to a segfault, test_must_fail diagnoses it as an error; "! " treats it as just another expected failure, which would let such a bug go unnoticed.
Accepts the following options:
ok=[,<...>]: Don't treat an exit caused by the given signal as error. Multiple signals can be specified as a comma separated list. Currently recognized signal names are: sigpipe, success. (Don't use 'success', use 'test_might_fail' instead.)
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test_might_fail []
Similar to test_must_fail, but tolerate success, too. Use this instead of " || :" to catch failures due to segv.
Accepts the same options as test_must_fail.
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test_cmp
Check whether the content of the file matches the file. This behaves like "cmp" but produces more helpful output when the test is run with "-v" option.
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test_cmp_rev
Check whether the rev points to the same commit as the rev.
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test_line_count (= | -lt | -ge | ...)
Check whether a file has the length it is expected to.
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test_path_is_file test_path_is_dir test_path_is_missing
Check if the named path is a file, if the named path is a directory, or if the named path does not exist, respectively, and fail otherwise.
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test_when_finished
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" && ... '
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test_atexit
Prepend <script> to a list of commands to run unconditionally to clean up before the test script exits, e.g. to stop a daemon:
test_expect_success 'test git daemon' ' git daemon & daemon_pid=$! && test_atexit 'kill $daemon_pid' && hello world '
The commands will be executed before the trash directory is removed, i.e. the atexit commands will still be able to access any pidfiles or socket files.
Note that these commands will be run even when a test script run with '--immediate' fails. Be careful with your atexit commands to minimize any changes to the failed state.
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test_write_lines
Write on standard output, one line per argument. Useful to prepare multi-line files in a compact form.
Example:
test_write_lines a b c d e f g >foo
Is a more compact equivalent of: cat >foo <<-EOF a b c d e f g EOF
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test_pause [options]
This command is useful for writing and debugging tests and must be removed before submitting. It halts the execution of the test and spawns a shell in the trash directory. Exit the shell to continue the test. Example:
test_expect_success 'test' ' git do-something >actual && test_pause && test_cmp expected actual '
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test_ln_s_add
This function helps systems whose filesystem does not support symbolic links. Use it to add a symbolic link entry to the index when it is not important that the file system entry is a symbolic link, i.e., instead of the sequence
ln -s foo bar && git add bar
Sometimes it is possible to split a test in a part that does not need the symbolic link in the file system and a part that does; then only the latter part need be protected by a SYMLINKS prerequisite (see below).
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test_path_is_executable
This tests whether a file is executable and prints an error message if not. This must be used only under the POSIXPERM prerequisite (see below).
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test_oid_init
This function loads facts and useful object IDs related to the hash algorithm(s) in use from the files in t/oid-info.
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test_oid_cache
This function reads per-hash algorithm information from standard input (usually a heredoc) in the format described in t/oid-info/README. This is useful for test-specific values, such as object IDs, which must vary based on the hash algorithm.
Certain fixed values, such as hash sizes and common placeholder object IDs, can be loaded with test_oid_init (described above).
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test_oid
This function looks up a value for the hash algorithm in use, based on the key given. The value must have been loaded using test_oid_init or test_oid_cache. Providing an unknown key is an error.
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yes []
This is often seen in modern UNIX but some platforms lack it, so the test harness overrides the platform implementation with a more limited one. Use this only when feeding a handful lines of output to the downstream---unlike the real version, it generates only up to 99 lines.
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test_bool_env
Given the name of an environment variable with a bool value, normalize its value to a 0 (true) or 1 (false or empty string) return code. Return with code corresponding to the given default value if the variable is unset. Abort the test script if either the value of the variable or the default are not valid bool values.
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.
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PYTHON
Git wasn't compiled with NO_PYTHON=YesPlease. Wrap any tests that need Python with this.
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PERL
Git wasn't compiled with NO_PERL=YesPlease.
Even without the PERL prerequisite, tests can assume there is a usable perl interpreter at $PERL_PATH, though it need not be particularly modern.
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POSIXPERM
The filesystem supports POSIX style permission bits.
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BSLASHPSPEC
Backslashes in pathspec are not directory separators. This is not set on Windows. See 6fd1106a for details.
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EXECKEEPSPID
The process retains the same pid across exec(2). See fb9a2bea for details.
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PIPE
The filesystem we're on supports creation of FIFOs (named pipes) via mkfifo(1).
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SYMLINKS
The filesystem we're on supports symbolic links. E.g. a FAT filesystem doesn't support these. See 704a3143 for details.
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SANITY
Test is not run by root user, and an attempt to write to an unwritable file is expected to fail correctly.
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PCRE
Git was compiled with support for PCRE. Wrap any tests that use git-grep --perl-regexp or git-grep -P in these.
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CASE_INSENSITIVE_FS
Test is run on a case insensitive file system.
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UTF8_NFD_TO_NFC
Test is run on a filesystem which converts decomposed utf-8 (nfd) to precomposed utf-8 (nfc).
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PTHREADS
Git wasn't compiled with NO_PTHREADS=YesPlease.
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REFFILES
Test is specific to packed/loose ref storage, and should be disabled for other ref storage backends
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 internals drastically. For these people, after making certain changes, not seeing failures from the basic test is a failure. Any Git core changes so drastic that they change even 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 an update whenever the internals change, 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 https://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.