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   1Core GIT Tests
   2==============
   3
   4This directory holds many test scripts for core GIT tools.  The
   5first part of this short document describes how to run the tests
   6and read their output.
   7
   8When fixing the tools or adding enhancements, you are strongly
   9encouraged to add tests in this directory to cover what you are
  10trying to fix or enhance.  The later part of this short document
  11describes how your test scripts should be organized.
  12
  13
  14Running Tests
  15-------------
  16
  17The easiest way to run tests is to say "make".  This runs all
  18the tests.
  19
  20    *** t0000-basic.sh ***
  21    ok 1 - .git/objects should be empty after git init in an empty repo.
  22    ok 2 - .git/objects should have 3 subdirectories.
  23    ok 3 - success is reported like this
  24    ...
  25    ok 43 - very long name in the index handled sanely
  26    # fixed 1 known breakage(s)
  27    # still have 1 known breakage(s)
  28    # passed all remaining 42 test(s)
  29    1..43
  30    *** t0001-init.sh ***
  31    ok 1 - plain
  32    ok 2 - plain with GIT_WORK_TREE
  33    ok 3 - plain bare
  34
  35Since the tests all output TAP (see http://testanything.org) they can
  36be run with any TAP harness. Here's an example of parallel testing
  37powered by a recent version of prove(1):
  38
  39    $ prove --timer --jobs 15 ./t[0-9]*.sh
  40    [19:17:33] ./t0005-signals.sh ................................... ok       36 ms
  41    [19:17:33] ./t0022-crlf-rename.sh ............................... ok       69 ms
  42    [19:17:33] ./t0024-crlf-archive.sh .............................. ok      154 ms
  43    [19:17:33] ./t0004-unwritable.sh ................................ ok      289 ms
  44    [19:17:33] ./t0002-gitfile.sh ................................... ok      480 ms
  45    ===(     102;0  25/?  6/?  5/?  16/?  1/?  4/?  2/?  1/?  3/?  1... )===
  46
  47prove and other harnesses come with a lot of useful options. The
  48--state option in particular is very useful:
  49
  50    # Repeat until no more failures
  51    $ prove -j 15 --state=failed,save ./t[0-9]*.sh
  52
  53You can give DEFAULT_TEST_TARGET=prove on the make command (or define it
  54in config.mak) to cause "make test" to run tests under prove.
  55GIT_PROVE_OPTS can be used to pass additional options, e.g.
  56
  57    $ make DEFAULT_TEST_TARGET=prove GIT_PROVE_OPTS='--timer --jobs 16' test
  58
  59You can also run each test individually from command line, like this:
  60
  61    $ sh ./t3010-ls-files-killed-modified.sh
  62    ok 1 - git update-index --add to add various paths.
  63    ok 2 - git ls-files -k to show killed files.
  64    ok 3 - validate git ls-files -k output.
  65    ok 4 - git ls-files -m to show modified files.
  66    ok 5 - validate git ls-files -m output.
  67    # passed all 5 test(s)
  68    1..5
  69
  70You can pass --verbose (or -v), --debug (or -d), and --immediate
  71(or -i) command line argument to the test, or by setting GIT_TEST_OPTS
  72appropriately before running "make".
  73
  74-v::
  75--verbose::
  76        This makes the test more verbose.  Specifically, the
  77        command being run and their output if any are also
  78        output.
  79
  80--verbose-only=<pattern>::
  81        Like --verbose, but the effect is limited to tests with
  82        numbers matching <pattern>.  The number matched against is
  83        simply the running count of the test within the file.
  84
  85-x::
  86        Turn on shell tracing (i.e., `set -x`) during the tests
  87        themselves. Implies `--verbose`. Note that in non-bash shells,
  88        this can cause failures in some tests which redirect and test
  89        the output of shell functions. Use with caution.
  90
  91-d::
  92--debug::
  93        This may help the person who is developing a new test.
  94        It causes the command defined with test_debug to run.
  95        The "trash" directory (used to store all temporary data
  96        during testing) is not deleted even if there are no
  97        failed tests so that you can inspect its contents after
  98        the test finished.
  99
 100-i::
 101--immediate::
 102        This causes the test to immediately exit upon the first
 103        failed test. Cleanup commands requested with
 104        test_when_finished are not executed if the test failed,
 105        in order to keep the state for inspection by the tester
 106        to diagnose the bug.
 107
 108-l::
 109--long-tests::
 110        This causes additional long-running tests to be run (where
 111        available), for more exhaustive testing.
 112
 113-r::
 114--run=<test-selector>::
 115        Run only the subset of tests indicated by
 116        <test-selector>.  See section "Skipping Tests" below for
 117        <test-selector> syntax.
 118
 119--valgrind=<tool>::
 120        Execute all Git binaries under valgrind tool <tool> and exit
 121        with status 126 on errors (just like regular tests, this will
 122        only stop the test script when running under -i).
 123
 124        Since it makes no sense to run the tests with --valgrind and
 125        not see any output, this option implies --verbose.  For
 126        convenience, it also implies --tee.
 127
 128        <tool> defaults to 'memcheck', just like valgrind itself.
 129        Other particularly useful choices include 'helgrind' and
 130        'drd', but you may use any tool recognized by your valgrind
 131        installation.
 132
 133        As a special case, <tool> can be 'memcheck-fast', which uses
 134        memcheck but disables --track-origins.  Use this if you are
 135        running tests in bulk, to see if there are _any_ memory
 136        issues.
 137
 138        Note that memcheck is run with the option --leak-check=no,
 139        as the git process is short-lived and some errors are not
 140        interesting. In order to run a single command under the same
 141        conditions manually, you should set GIT_VALGRIND to point to
 142        the 't/valgrind/' directory and use the commands under
 143        't/valgrind/bin/'.
 144
 145--valgrind-only=<pattern>::
 146        Like --valgrind, but the effect is limited to tests with
 147        numbers matching <pattern>.  The number matched against is
 148        simply the running count of the test within the file.
 149
 150--tee::
 151        In addition to printing the test output to the terminal,
 152        write it to files named 't/test-results/$TEST_NAME.out'.
 153        As the names depend on the tests' file names, it is safe to
 154        run the tests with this option in parallel.
 155
 156--verbose-log::
 157        Write verbose output to the same logfile as `--tee`, but do
 158        _not_ write it to stdout. Unlike `--tee --verbose`, this option
 159        is safe to use when stdout is being consumed by a TAP parser
 160        like `prove`. Implies `--tee` and `--verbose`.
 161
 162--with-dashes::
 163        By default tests are run without dashed forms of
 164        commands (like git-commit) in the PATH (it only uses
 165        wrappers from ../bin-wrappers).  Use this option to include
 166        the build directory (..) in the PATH, which contains all
 167        the dashed forms of commands.  This option is currently
 168        implied by other options like --valgrind and
 169        GIT_TEST_INSTALLED.
 170
 171--root=<directory>::
 172        Create "trash" directories used to store all temporary data during
 173        testing under <directory>, instead of the t/ directory.
 174        Using this option with a RAM-based filesystem (such as tmpfs)
 175        can massively speed up the test suite.
 176
 177--chain-lint::
 178--no-chain-lint::
 179        If --chain-lint is enabled, the test harness will check each
 180        test to make sure that it properly "&&-chains" all commands (so
 181        that a failure in the middle does not go unnoticed by the final
 182        exit code of the test). This check is performed in addition to
 183        running the tests themselves. You may also enable or disable
 184        this feature by setting the GIT_TEST_CHAIN_LINT environment
 185        variable to "1" or "0", respectively.
 186
 187You can also set the GIT_TEST_INSTALLED environment variable to
 188the bindir of an existing git installation to test that installation.
 189You still need to have built this git sandbox, from which various
 190test-* support programs, templates, and perl libraries are used.
 191If your installed git is incomplete, it will silently test parts of
 192your built version instead.
 193
 194When using GIT_TEST_INSTALLED, you can also set GIT_TEST_EXEC_PATH to
 195override the location of the dashed-form subcommands (what
 196GIT_EXEC_PATH would be used for during normal operation).
 197GIT_TEST_EXEC_PATH defaults to `$GIT_TEST_INSTALLED/git --exec-path`.
 198
 199
 200Skipping Tests
 201--------------
 202
 203In some environments, certain tests have no way of succeeding
 204due to platform limitation, such as lack of 'unzip' program, or
 205filesystem that do not allow arbitrary sequence of non-NUL bytes
 206as pathnames.
 207
 208You should be able to say something like
 209
 210    $ GIT_SKIP_TESTS=t9200.8 sh ./t9200-git-cvsexport-commit.sh
 211
 212and even:
 213
 214    $ GIT_SKIP_TESTS='t[0-4]??? t91?? t9200.8' make
 215
 216to omit such tests.  The value of the environment variable is a
 217SP separated list of patterns that tells which tests to skip,
 218and either can match the "t[0-9]{4}" part to skip the whole
 219test, or t[0-9]{4} followed by ".$number" to say which
 220particular test to skip.
 221
 222For an individual test suite --run could be used to specify that
 223only some tests should be run or that some tests should be
 224excluded from a run.
 225
 226The argument for --run is a list of individual test numbers or
 227ranges with an optional negation prefix that define what tests in
 228a test suite to include in the run.  A range is two numbers
 229separated with a dash and matches a range of tests with both ends
 230been included.  You may omit the first or the second number to
 231mean "from the first test" or "up to the very last test"
 232respectively.
 233
 234Optional prefix of '!' means that the test or a range of tests
 235should be excluded from the run.
 236
 237If --run starts with an unprefixed number or range the initial
 238set of tests to run is empty. If the first item starts with '!'
 239all the tests are added to the initial set.  After initial set is
 240determined every test number or range is added or excluded from
 241the set one by one, from left to right.
 242
 243Individual numbers or ranges could be separated either by a space
 244or a comma.
 245
 246For example, to run only tests up to a specific test (21), one
 247could do this:
 248
 249    $ sh ./t9200-git-cvsexport-commit.sh --run='1-21'
 250
 251or this:
 252
 253    $ sh ./t9200-git-cvsexport-commit.sh --run='-21'
 254
 255Common case is to run several setup tests (1, 2, 3) and then a
 256specific test (21) that relies on that setup:
 257
 258    $ sh ./t9200-git-cvsexport-commit.sh --run='1 2 3 21'
 259
 260or:
 261
 262    $ sh ./t9200-git-cvsexport-commit.sh --run=1,2,3,21
 263
 264or:
 265
 266    $ sh ./t9200-git-cvsexport-commit.sh --run='-3 21'
 267
 268As noted above, the test set is built by going through the items
 269from left to right, so this:
 270
 271    $ sh ./t9200-git-cvsexport-commit.sh --run='1-4 !3'
 272
 273will run tests 1, 2, and 4.  Items that come later have higher
 274precedence.  It means that this:
 275
 276    $ sh ./t9200-git-cvsexport-commit.sh --run='!3 1-4'
 277
 278would just run tests from 1 to 4, including 3.
 279
 280You may use negation with ranges.  The following will run all
 281test in the test suite except from 7 up to 11:
 282
 283    $ sh ./t9200-git-cvsexport-commit.sh --run='!7-11'
 284
 285Some tests in a test suite rely on the previous tests performing
 286certain actions, specifically some tests are designated as
 287"setup" test, so you cannot _arbitrarily_ disable one test and
 288expect the rest to function correctly.
 289
 290--run is mostly useful when you want to focus on a specific test
 291and know what setup is needed for it.  Or when you want to run
 292everything up to a certain test.
 293
 294
 295Naming Tests
 296------------
 297
 298The test files are named as:
 299
 300        tNNNN-commandname-details.sh
 301
 302where N is a decimal digit.
 303
 304First digit tells the family:
 305
 306        0 - the absolute basics and global stuff
 307        1 - the basic commands concerning database
 308        2 - the basic commands concerning the working tree
 309        3 - the other basic commands (e.g. ls-files)
 310        4 - the diff commands
 311        5 - the pull and exporting commands
 312        6 - the revision tree commands (even e.g. merge-base)
 313        7 - the porcelainish commands concerning the working tree
 314        8 - the porcelainish commands concerning forensics
 315        9 - the git tools
 316
 317Second digit tells the particular command we are testing.
 318
 319Third digit (optionally) tells the particular switch or group of switches
 320we are testing.
 321
 322If you create files under t/ directory (i.e. here) that is not
 323the top-level test script, never name the file to match the above
 324pattern.  The Makefile here considers all such files as the
 325top-level test script and tries to run all of them.  Care is
 326especially needed if you are creating a common test library
 327file, similar to test-lib.sh, because such a library file may
 328not be suitable for standalone execution.
 329
 330
 331Writing Tests
 332-------------
 333
 334The test script is written as a shell script.  It should start
 335with the standard "#!/bin/sh" with copyright notices, and an
 336assignment to variable 'test_description', like this:
 337
 338        #!/bin/sh
 339        #
 340        # Copyright (c) 2005 Junio C Hamano
 341        #
 342
 343        test_description='xxx test (option --frotz)
 344
 345        This test registers the following structure in the cache
 346        and tries to run git-ls-files with option --frotz.'
 347
 348
 349Source 'test-lib.sh'
 350--------------------
 351
 352After assigning test_description, the test script should source
 353test-lib.sh like this:
 354
 355        . ./test-lib.sh
 356
 357This test harness library does the following things:
 358
 359 - If the script is invoked with command line argument --help
 360   (or -h), it shows the test_description and exits.
 361
 362 - Creates an empty test directory with an empty .git/objects database
 363   and chdir(2) into it.  This directory is 't/trash
 364   directory.$test_name_without_dotsh', with t/ subject to change by
 365   the --root option documented above.
 366
 367 - Defines standard test helper functions for your scripts to
 368   use.  These functions are designed to make all scripts behave
 369   consistently when command line arguments --verbose (or -v),
 370   --debug (or -d), and --immediate (or -i) is given.
 371
 372Do's, don'ts & things to keep in mind
 373-------------------------------------
 374
 375Here are a few examples of things you probably should and shouldn't do
 376when writing tests.
 377
 378Do:
 379
 380 - Put all code inside test_expect_success and other assertions.
 381
 382   Even code that isn't a test per se, but merely some setup code
 383   should be inside a test assertion.
 384
 385 - Chain your test assertions
 386
 387   Write test code like this:
 388
 389        git merge foo &&
 390        git push bar &&
 391        test ...
 392
 393   Instead of:
 394
 395        git merge hla
 396        git push gh
 397        test ...
 398
 399   That way all of the commands in your tests will succeed or fail. If
 400   you must ignore the return value of something, consider using a
 401   helper function (e.g. use sane_unset instead of unset, in order
 402   to avoid unportable return value for unsetting a variable that was
 403   already unset), or prepending the command with test_might_fail or
 404   test_must_fail.
 405
 406 - Check the test coverage for your tests. See the "Test coverage"
 407   below.
 408
 409   Don't blindly follow test coverage metrics; if a new function you added
 410   doesn't have any coverage, then you're probably doing something wrong,
 411   but having 100% coverage doesn't necessarily mean that you tested
 412   everything.
 413
 414   Tests that are likely to smoke out future regressions are better
 415   than tests that just inflate the coverage metrics.
 416
 417 - When a test checks for an absolute path that a git command generated,
 418   construct the expected value using $(pwd) rather than $PWD,
 419   $TEST_DIRECTORY, or $TRASH_DIRECTORY. It makes a difference on
 420   Windows, where the shell (MSYS bash) mangles absolute path names.
 421   For details, see the commit message of 4114156ae9.
 422
 423Don't:
 424
 425 - exit() within a <script> part.
 426
 427   The harness will catch this as a programming error of the test.
 428   Use test_done instead if you need to stop the tests early (see
 429   "Skipping tests" below).
 430
 431 - use '! git cmd' when you want to make sure the git command exits
 432   with failure in a controlled way by calling "die()".  Instead,
 433   use 'test_must_fail git cmd'.  This will signal a failure if git
 434   dies in an unexpected way (e.g. segfault).
 435
 436   On the other hand, don't use test_must_fail for running regular
 437   platform commands; just use '! cmd'.  We are not in the business
 438   of verifying that the world given to us sanely works.
 439
 440 - use perl without spelling it as "$PERL_PATH". This is to help our
 441   friends on Windows where the platform Perl often adds CR before
 442   the end of line, and they bundle Git with a version of Perl that
 443   does not do so, whose path is specified with $PERL_PATH. Note that we
 444   provide a "perl" function which uses $PERL_PATH under the hood, so
 445   you do not need to worry when simply running perl in the test scripts
 446   (but you do, for example, on a shebang line or in a sub script
 447   created via "write_script").
 448
 449 - use sh without spelling it as "$SHELL_PATH", when the script can
 450   be misinterpreted by broken platform shell (e.g. Solaris).
 451
 452 - chdir around in tests.  It is not sufficient to chdir to
 453   somewhere and then chdir back to the original location later in
 454   the test, as any intermediate step can fail and abort the test,
 455   causing the next test to start in an unexpected directory.  Do so
 456   inside a subshell if necessary.
 457
 458 - Break the TAP output
 459
 460   The raw output from your test may be interpreted by a TAP harness. TAP
 461   harnesses will ignore everything they don't know about, but don't step
 462   on their toes in these areas:
 463
 464   - Don't print lines like "$x..$y" where $x and $y are integers.
 465
 466   - Don't print lines that begin with "ok" or "not ok".
 467
 468   TAP harnesses expect a line that begins with either "ok" and "not
 469   ok" to signal a test passed or failed (and our harness already
 470   produces such lines), so your script shouldn't emit such lines to
 471   their output.
 472
 473   You can glean some further possible issues from the TAP grammar
 474   (see https://metacpan.org/pod/TAP::Parser::Grammar#TAP-GRAMMAR)
 475   but the best indication is to just run the tests with prove(1),
 476   it'll complain if anything is amiss.
 477
 478Keep in mind:
 479
 480 - Inside the <script> part, the standard output and standard error
 481   streams are discarded, and the test harness only reports "ok" or
 482   "not ok" to the end user running the tests. Under --verbose, they
 483   are shown to help debugging the tests.
 484
 485
 486Skipping tests
 487--------------
 488
 489If you need to skip tests you should do so by using the three-arg form
 490of the test_* functions (see the "Test harness library" section
 491below), e.g.:
 492
 493    test_expect_success PERL 'I need Perl' '
 494        perl -e "hlagh() if unf_unf()"
 495    '
 496
 497The advantage of skipping tests like this is that platforms that don't
 498have the PERL and other optional dependencies get an indication of how
 499many tests they're missing.
 500
 501If the test code is too hairy for that (i.e. does a lot of setup work
 502outside test assertions) you can also skip all remaining tests by
 503setting skip_all and immediately call test_done:
 504
 505        if ! test_have_prereq PERL
 506        then
 507            skip_all='skipping perl interface tests, perl not available'
 508            test_done
 509        fi
 510
 511The string you give to skip_all will be used as an explanation for why
 512the test was skipped.
 513
 514End with test_done
 515------------------
 516
 517Your script will be a sequence of tests, using helper functions
 518from the test harness library.  At the end of the script, call
 519'test_done'.
 520
 521
 522Test harness library
 523--------------------
 524
 525There are a handful helper functions defined in the test harness
 526library for your script to use.
 527
 528 - test_expect_success [<prereq>] <message> <script>
 529
 530   Usually takes two strings as parameters, and evaluates the
 531   <script>.  If it yields success, test is considered
 532   successful.  <message> should state what it is testing.
 533
 534   Example:
 535
 536        test_expect_success \
 537            'git-write-tree should be able to write an empty tree.' \
 538            'tree=$(git-write-tree)'
 539
 540   If you supply three parameters the first will be taken to be a
 541   prerequisite; see the test_set_prereq and test_have_prereq
 542   documentation below:
 543
 544        test_expect_success TTY 'git --paginate rev-list uses a pager' \
 545            ' ... '
 546
 547   You can also supply a comma-separated list of prerequisites, in the
 548   rare case where your test depends on more than one:
 549
 550        test_expect_success PERL,PYTHON 'yo dawg' \
 551            ' test $(perl -E 'print eval "1 +" . qx[python -c "print 2"]') == "4" '
 552
 553 - test_expect_failure [<prereq>] <message> <script>
 554
 555   This is NOT the opposite of test_expect_success, but is used
 556   to mark a test that demonstrates a known breakage.  Unlike
 557   the usual test_expect_success tests, which say "ok" on
 558   success and "FAIL" on failure, this will say "FIXED" on
 559   success and "still broken" on failure.  Failures from these
 560   tests won't cause -i (immediate) to stop.
 561
 562   Like test_expect_success this function can optionally use a three
 563   argument invocation with a prerequisite as the first argument.
 564
 565 - test_debug <script>
 566
 567   This takes a single argument, <script>, and evaluates it only
 568   when the test script is started with --debug command line
 569   argument.  This is primarily meant for use during the
 570   development of a new test script.
 571
 572 - debug <git-command>
 573
 574   Run a git command inside a debugger. This is primarily meant for
 575   use when debugging a failing test script.
 576
 577 - test_done
 578
 579   Your test script must have test_done at the end.  Its purpose
 580   is to summarize successes and failures in the test script and
 581   exit with an appropriate error code.
 582
 583 - test_tick
 584
 585   Make commit and tag names consistent by setting the author and
 586   committer times to defined state.  Subsequent calls will
 587   advance the times by a fixed amount.
 588
 589 - test_commit <message> [<filename> [<contents>]]
 590
 591   Creates a commit with the given message, committing the given
 592   file with the given contents (default for both is to reuse the
 593   message string), and adds a tag (again reusing the message
 594   string as name).  Calls test_tick to make the SHA-1s
 595   reproducible.
 596
 597 - test_merge <message> <commit-or-tag>
 598
 599   Merges the given rev using the given message.  Like test_commit,
 600   creates a tag and calls test_tick before committing.
 601
 602 - test_set_prereq <prereq>
 603
 604   Set a test prerequisite to be used later with test_have_prereq. The
 605   test-lib will set some prerequisites for you, see the
 606   "Prerequisites" section below for a full list of these.
 607
 608   Others you can set yourself and use later with either
 609   test_have_prereq directly, or the three argument invocation of
 610   test_expect_success and test_expect_failure.
 611
 612 - test_have_prereq <prereq>
 613
 614   Check if we have a prerequisite previously set with test_set_prereq.
 615   The most common way to use this explicitly (as opposed to the
 616   implicit use when an argument is passed to test_expect_*) is to skip
 617   all the tests at the start of the test script if we don't have some
 618   essential prerequisite:
 619
 620        if ! test_have_prereq PERL
 621        then
 622            skip_all='skipping perl interface tests, perl not available'
 623            test_done
 624        fi
 625
 626 - test_external [<prereq>] <message> <external> <script>
 627
 628   Execute a <script> with an <external> interpreter (like perl). This
 629   was added for tests like t9700-perl-git.sh which do most of their
 630   work in an external test script.
 631
 632        test_external \
 633            'GitwebCache::*FileCache*' \
 634            perl "$TEST_DIRECTORY"/t9503/test_cache_interface.pl
 635
 636   If the test is outputting its own TAP you should set the
 637   test_external_has_tap variable somewhere before calling the first
 638   test_external* function. See t9700-perl-git.sh for an example.
 639
 640        # The external test will outputs its own plan
 641        test_external_has_tap=1
 642
 643 - test_external_without_stderr [<prereq>] <message> <external> <script>
 644
 645   Like test_external but fail if there's any output on stderr,
 646   instead of checking the exit code.
 647
 648        test_external_without_stderr \
 649            'Perl API' \
 650            perl "$TEST_DIRECTORY"/t9700/test.pl
 651
 652 - test_expect_code <exit-code> <command>
 653
 654   Run a command and ensure that it exits with the given exit code.
 655   For example:
 656
 657        test_expect_success 'Merge with d/f conflicts' '
 658                test_expect_code 1 git merge "merge msg" B master
 659        '
 660
 661 - test_must_fail <git-command>
 662
 663   Run a git command and ensure it fails in a controlled way.  Use
 664   this instead of "! <git-command>".  When git-command dies due to a
 665   segfault, test_must_fail diagnoses it as an error; "! <git-command>"
 666   treats it as just another expected failure, which would let such a
 667   bug go unnoticed.
 668
 669 - test_might_fail <git-command>
 670
 671   Similar to test_must_fail, but tolerate success, too.  Use this
 672   instead of "<git-command> || :" to catch failures due to segv.
 673
 674 - test_cmp <expected> <actual>
 675
 676   Check whether the content of the <actual> file matches the
 677   <expected> file.  This behaves like "cmp" but produces more
 678   helpful output when the test is run with "-v" option.
 679
 680 - test_line_count (= | -lt | -ge | ...) <length> <file>
 681
 682   Check whether a file has the length it is expected to.
 683
 684 - test_path_is_file <path> [<diagnosis>]
 685   test_path_is_dir <path> [<diagnosis>]
 686   test_path_is_missing <path> [<diagnosis>]
 687
 688   Check if the named path is a file, if the named path is a
 689   directory, or if the named path does not exist, respectively,
 690   and fail otherwise, showing the <diagnosis> text.
 691
 692 - test_when_finished <script>
 693
 694   Prepend <script> to a list of commands to run to clean up
 695   at the end of the current test.  If some clean-up command
 696   fails, the test will not pass.
 697
 698   Example:
 699
 700        test_expect_success 'branch pointing to non-commit' '
 701                git rev-parse HEAD^{tree} >.git/refs/heads/invalid &&
 702                test_when_finished "git update-ref -d refs/heads/invalid" &&
 703                ...
 704        '
 705
 706 - test_write_lines <lines>
 707
 708   Write <lines> on standard output, one line per argument.
 709   Useful to prepare multi-line files in a compact form.
 710
 711   Example:
 712
 713        test_write_lines a b c d e f g >foo
 714
 715   Is a more compact equivalent of:
 716        cat >foo <<-EOF
 717        a
 718        b
 719        c
 720        d
 721        e
 722        f
 723        g
 724        EOF
 725
 726
 727 - test_pause
 728
 729        This command is useful for writing and debugging tests and must be
 730        removed before submitting. It halts the execution of the test and
 731        spawns a shell in the trash directory. Exit the shell to continue
 732        the test. Example:
 733
 734        test_expect_success 'test' '
 735                git do-something >actual &&
 736                test_pause &&
 737                test_cmp expected actual
 738        '
 739
 740 - test_ln_s_add <path1> <path2>
 741
 742   This function helps systems whose filesystem does not support symbolic
 743   links. Use it to add a symbolic link entry to the index when it is not
 744   important that the file system entry is a symbolic link, i.e., instead
 745   of the sequence
 746
 747        ln -s foo bar &&
 748        git add bar
 749
 750   Sometimes it is possible to split a test in a part that does not need
 751   the symbolic link in the file system and a part that does; then only
 752   the latter part need be protected by a SYMLINKS prerequisite (see below).
 753
 754Prerequisites
 755-------------
 756
 757These are the prerequisites that the test library predefines with
 758test_have_prereq.
 759
 760See the prereq argument to the test_* functions in the "Test harness
 761library" section above and the "test_have_prereq" function for how to
 762use these, and "test_set_prereq" for how to define your own.
 763
 764 - PYTHON
 765
 766   Git wasn't compiled with NO_PYTHON=YesPlease. Wrap any tests that
 767   need Python with this.
 768
 769 - PERL
 770
 771   Git wasn't compiled with NO_PERL=YesPlease.
 772
 773   Even without the PERL prerequisite, tests can assume there is a
 774   usable perl interpreter at $PERL_PATH, though it need not be
 775   particularly modern.
 776
 777 - POSIXPERM
 778
 779   The filesystem supports POSIX style permission bits.
 780
 781 - BSLASHPSPEC
 782
 783   Backslashes in pathspec are not directory separators. This is not
 784   set on Windows. See 6fd1106a for details.
 785
 786 - EXECKEEPSPID
 787
 788   The process retains the same pid across exec(2). See fb9a2bea for
 789   details.
 790
 791 - PIPE
 792
 793   The filesystem we're on supports creation of FIFOs (named pipes)
 794   via mkfifo(1).
 795
 796 - SYMLINKS
 797
 798   The filesystem we're on supports symbolic links. E.g. a FAT
 799   filesystem doesn't support these. See 704a3143 for details.
 800
 801 - SANITY
 802
 803   Test is not run by root user, and an attempt to write to an
 804   unwritable file is expected to fail correctly.
 805
 806 - PCRE
 807
 808   Git was compiled with support for PCRE. Wrap any tests
 809   that use git-grep --perl-regexp or git-grep -P in these.
 810
 811 - CASE_INSENSITIVE_FS
 812
 813   Test is run on a case insensitive file system.
 814
 815 - UTF8_NFD_TO_NFC
 816
 817   Test is run on a filesystem which converts decomposed utf-8 (nfd)
 818   to precomposed utf-8 (nfc).
 819
 820 - PTHREADS
 821
 822   Git wasn't compiled with NO_PTHREADS=YesPlease.
 823
 824Tips for Writing Tests
 825----------------------
 826
 827As with any programming projects, existing programs are the best
 828source of the information.  However, do _not_ emulate
 829t0000-basic.sh when writing your tests.  The test is special in
 830that it tries to validate the very core of GIT.  For example, it
 831knows that there will be 256 subdirectories under .git/objects/,
 832and it knows that the object ID of an empty tree is a certain
 83340-byte string.  This is deliberately done so in t0000-basic.sh
 834because the things the very basic core test tries to achieve is
 835to serve as a basis for people who are changing the GIT internal
 836drastically.  For these people, after making certain changes,
 837not seeing failures from the basic test _is_ a failure.  And
 838such drastic changes to the core GIT that even changes these
 839otherwise supposedly stable object IDs should be accompanied by
 840an update to t0000-basic.sh.
 841
 842However, other tests that simply rely on basic parts of the core
 843GIT working properly should not have that level of intimate
 844knowledge of the core GIT internals.  If all the test scripts
 845hardcoded the object IDs like t0000-basic.sh does, that defeats
 846the purpose of t0000-basic.sh, which is to isolate that level of
 847validation in one place.  Your test also ends up needing
 848updating when such a change to the internal happens, so do _not_
 849do it and leave the low level of validation to t0000-basic.sh.
 850
 851Test coverage
 852-------------
 853
 854You can use the coverage tests to find code paths that are not being
 855used or properly exercised yet.
 856
 857To do that, run the coverage target at the top-level (not in the t/
 858directory):
 859
 860    make coverage
 861
 862That'll compile Git with GCC's coverage arguments, and generate a test
 863report with gcov after the tests finish. Running the coverage tests
 864can take a while, since running the tests in parallel is incompatible
 865with GCC's coverage mode.
 866
 867After the tests have run you can generate a list of untested
 868functions:
 869
 870    make coverage-untested-functions
 871
 872You can also generate a detailed per-file HTML report using the
 873Devel::Cover module. To install it do:
 874
 875   # On Debian or Ubuntu:
 876   sudo aptitude install libdevel-cover-perl
 877
 878   # From the CPAN with cpanminus
 879   curl -L http://cpanmin.us | perl - --sudo --self-upgrade
 880   cpanm --sudo Devel::Cover
 881
 882Then, at the top-level:
 883
 884    make cover_db_html
 885
 886That'll generate a detailed cover report in the "cover_db_html"
 887directory, which you can then copy to a webserver, or inspect locally
 888in a browser.