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
------------------
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 $(perl -E 'print eval "1 +" . qx[python -c "print 2"]') == "4" '
+
- test_expect_failure [<prereq>] <message> <script>
This is NOT the opposite of test_expect_success, but is used
- test_set_prereq SOME_PREREQ
Set a test prerequisite to be used later with test_have_prereq. The
- test-lib will set some prerequisites for you, e.g. PERL and PYTHON
- which are derived from ./GIT-BUILD-OPTIONS (grep test_set_prereq
- test-lib.sh for more). Others you can set yourself and use later
- with either test_have_prereq directly, or the three argument
- invocation of test_expect_success and test_expect_failure.
+ test-lib will set some prerequisites for you, see the
+ "Prerequisites" section below for a full list of these.
+
+ Others you can set yourself and use later with either
+ test_have_prereq directly, or the three argument invocation of
+ test_expect_success and test_expect_failure.
- test_have_prereq SOME PREREQ
'Perl API' \
"$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_path_is_file <file> [<diagnosis>]
+ test_path_is_dir <dir> [<diagnosis>]
+ test_path_is_missing <path> [<diagnosis>]
+
+ Check whether a file/directory exists or doesn't. <diagnosis> will
+ be displayed if the test fails.
+
+ - 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
----------------------
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.