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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`.
  88        Ignored in test scripts that set the variable 'test_untraceable'
  89        to a non-empty value, unless it's run with a Bash version
  90        supporting BASH_XTRACEFD, i.e. v4.1 or later.
  91
  92-d::
  93--debug::
  94        This may help the person who is developing a new test.
  95        It causes the command defined with test_debug to run.
  96        The "trash" directory (used to store all temporary data
  97        during testing) is not deleted even if there are no
  98        failed tests so that you can inspect its contents after
  99        the test finished.
 100
 101-i::
 102--immediate::
 103        This causes the test to immediately exit upon the first
 104        failed test. Cleanup commands requested with
 105        test_when_finished are not executed if the test failed,
 106        in order to keep the state for inspection by the tester
 107        to diagnose the bug.
 108
 109-l::
 110--long-tests::
 111        This causes additional long-running tests to be run (where
 112        available), for more exhaustive testing.
 113
 114-r::
 115--run=<test-selector>::
 116        Run only the subset of tests indicated by
 117        <test-selector>.  See section "Skipping Tests" below for
 118        <test-selector> syntax.
 119
 120--valgrind=<tool>::
 121        Execute all Git binaries under valgrind tool <tool> and exit
 122        with status 126 on errors (just like regular tests, this will
 123        only stop the test script when running under -i).
 124
 125        Since it makes no sense to run the tests with --valgrind and
 126        not see any output, this option implies --verbose.  For
 127        convenience, it also implies --tee.
 128
 129        <tool> defaults to 'memcheck', just like valgrind itself.
 130        Other particularly useful choices include 'helgrind' and
 131        'drd', but you may use any tool recognized by your valgrind
 132        installation.
 133
 134        As a special case, <tool> can be 'memcheck-fast', which uses
 135        memcheck but disables --track-origins.  Use this if you are
 136        running tests in bulk, to see if there are _any_ memory
 137        issues.
 138
 139        Note that memcheck is run with the option --leak-check=no,
 140        as the git process is short-lived and some errors are not
 141        interesting. In order to run a single command under the same
 142        conditions manually, you should set GIT_VALGRIND to point to
 143        the 't/valgrind/' directory and use the commands under
 144        't/valgrind/bin/'.
 145
 146--valgrind-only=<pattern>::
 147        Like --valgrind, but the effect is limited to tests with
 148        numbers matching <pattern>.  The number matched against is
 149        simply the running count of the test within the file.
 150
 151--tee::
 152        In addition to printing the test output to the terminal,
 153        write it to files named 't/test-results/$TEST_NAME.out'.
 154        As the names depend on the tests' file names, it is safe to
 155        run the tests with this option in parallel.
 156
 157--verbose-log::
 158        Write verbose output to the same logfile as `--tee`, but do
 159        _not_ write it to stdout. Unlike `--tee --verbose`, this option
 160        is safe to use when stdout is being consumed by a TAP parser
 161        like `prove`. Implies `--tee` and `--verbose`.
 162
 163--with-dashes::
 164        By default tests are run without dashed forms of
 165        commands (like git-commit) in the PATH (it only uses
 166        wrappers from ../bin-wrappers).  Use this option to include
 167        the build directory (..) in the PATH, which contains all
 168        the dashed forms of commands.  This option is currently
 169        implied by other options like --valgrind and
 170        GIT_TEST_INSTALLED.
 171
 172--root=<directory>::
 173        Create "trash" directories used to store all temporary data during
 174        testing under <directory>, instead of the t/ directory.
 175        Using this option with a RAM-based filesystem (such as tmpfs)
 176        can massively speed up the test suite.
 177
 178--chain-lint::
 179--no-chain-lint::
 180        If --chain-lint is enabled, the test harness will check each
 181        test to make sure that it properly "&&-chains" all commands (so
 182        that a failure in the middle does not go unnoticed by the final
 183        exit code of the test). This check is performed in addition to
 184        running the tests themselves. You may also enable or disable
 185        this feature by setting the GIT_TEST_CHAIN_LINT environment
 186        variable to "1" or "0", respectively.
 187
 188You can also set the GIT_TEST_INSTALLED environment variable to
 189the bindir of an existing git installation to test that installation.
 190You still need to have built this git sandbox, from which various
 191test-* support programs, templates, and perl libraries are used.
 192If your installed git is incomplete, it will silently test parts of
 193your built version instead.
 194
 195When using GIT_TEST_INSTALLED, you can also set GIT_TEST_EXEC_PATH to
 196override the location of the dashed-form subcommands (what
 197GIT_EXEC_PATH would be used for during normal operation).
 198GIT_TEST_EXEC_PATH defaults to `$GIT_TEST_INSTALLED/git --exec-path`.
 199
 200
 201Skipping Tests
 202--------------
 203
 204In some environments, certain tests have no way of succeeding
 205due to platform limitation, such as lack of 'unzip' program, or
 206filesystem that do not allow arbitrary sequence of non-NUL bytes
 207as pathnames.
 208
 209You should be able to say something like
 210
 211    $ GIT_SKIP_TESTS=t9200.8 sh ./t9200-git-cvsexport-commit.sh
 212
 213and even:
 214
 215    $ GIT_SKIP_TESTS='t[0-4]??? t91?? t9200.8' make
 216
 217to omit such tests.  The value of the environment variable is a
 218SP separated list of patterns that tells which tests to skip,
 219and either can match the "t[0-9]{4}" part to skip the whole
 220test, or t[0-9]{4} followed by ".$number" to say which
 221particular test to skip.
 222
 223For an individual test suite --run could be used to specify that
 224only some tests should be run or that some tests should be
 225excluded from a run.
 226
 227The argument for --run is a list of individual test numbers or
 228ranges with an optional negation prefix that define what tests in
 229a test suite to include in the run.  A range is two numbers
 230separated with a dash and matches a range of tests with both ends
 231been included.  You may omit the first or the second number to
 232mean "from the first test" or "up to the very last test"
 233respectively.
 234
 235Optional prefix of '!' means that the test or a range of tests
 236should be excluded from the run.
 237
 238If --run starts with an unprefixed number or range the initial
 239set of tests to run is empty. If the first item starts with '!'
 240all the tests are added to the initial set.  After initial set is
 241determined every test number or range is added or excluded from
 242the set one by one, from left to right.
 243
 244Individual numbers or ranges could be separated either by a space
 245or a comma.
 246
 247For example, to run only tests up to a specific test (21), one
 248could do this:
 249
 250    $ sh ./t9200-git-cvsexport-commit.sh --run='1-21'
 251
 252or this:
 253
 254    $ sh ./t9200-git-cvsexport-commit.sh --run='-21'
 255
 256Common case is to run several setup tests (1, 2, 3) and then a
 257specific test (21) that relies on that setup:
 258
 259    $ sh ./t9200-git-cvsexport-commit.sh --run='1 2 3 21'
 260
 261or:
 262
 263    $ sh ./t9200-git-cvsexport-commit.sh --run=1,2,3,21
 264
 265or:
 266
 267    $ sh ./t9200-git-cvsexport-commit.sh --run='-3 21'
 268
 269As noted above, the test set is built by going through the items
 270from left to right, so this:
 271
 272    $ sh ./t9200-git-cvsexport-commit.sh --run='1-4 !3'
 273
 274will run tests 1, 2, and 4.  Items that come later have higher
 275precedence.  It means that this:
 276
 277    $ sh ./t9200-git-cvsexport-commit.sh --run='!3 1-4'
 278
 279would just run tests from 1 to 4, including 3.
 280
 281You may use negation with ranges.  The following will run all
 282test in the test suite except from 7 up to 11:
 283
 284    $ sh ./t9200-git-cvsexport-commit.sh --run='!7-11'
 285
 286Some tests in a test suite rely on the previous tests performing
 287certain actions, specifically some tests are designated as
 288"setup" test, so you cannot _arbitrarily_ disable one test and
 289expect the rest to function correctly.
 290
 291--run is mostly useful when you want to focus on a specific test
 292and know what setup is needed for it.  Or when you want to run
 293everything up to a certain test.
 294
 295
 296Running tests with special setups
 297---------------------------------
 298
 299The whole test suite could be run to test some special features
 300that cannot be easily covered by a few specific test cases. These
 301could be enabled by running the test suite with correct GIT_TEST_
 302environment set.
 303
 304GIT_TEST_SPLIT_INDEX=<boolean> forces split-index mode on the whole
 305test suite. Accept any boolean values that are accepted by git-config.
 306
 307GIT_TEST_FULL_IN_PACK_ARRAY=<boolean> exercises the uncommon
 308pack-objects code path where there are more than 1024 packs even if
 309the actual number of packs in repository is below this limit. Accept
 310any boolean values that are accepted by git-config.
 311
 312GIT_TEST_OE_SIZE=<n> exercises the uncommon pack-objects code path
 313where we do not cache object size in memory and read it from existing
 314packs on demand. This normally only happens when the object size is
 315over 2GB. This variable forces the code path on any object larger than
 316<n> bytes.
 317
 318Naming Tests
 319------------
 320
 321The test files are named as:
 322
 323        tNNNN-commandname-details.sh
 324
 325where N is a decimal digit.
 326
 327First digit tells the family:
 328
 329        0 - the absolute basics and global stuff
 330        1 - the basic commands concerning database
 331        2 - the basic commands concerning the working tree
 332        3 - the other basic commands (e.g. ls-files)
 333        4 - the diff commands
 334        5 - the pull and exporting commands
 335        6 - the revision tree commands (even e.g. merge-base)
 336        7 - the porcelainish commands concerning the working tree
 337        8 - the porcelainish commands concerning forensics
 338        9 - the git tools
 339
 340Second digit tells the particular command we are testing.
 341
 342Third digit (optionally) tells the particular switch or group of switches
 343we are testing.
 344
 345If you create files under t/ directory (i.e. here) that is not
 346the top-level test script, never name the file to match the above
 347pattern.  The Makefile here considers all such files as the
 348top-level test script and tries to run all of them.  Care is
 349especially needed if you are creating a common test library
 350file, similar to test-lib.sh, because such a library file may
 351not be suitable for standalone execution.
 352
 353
 354Writing Tests
 355-------------
 356
 357The test script is written as a shell script.  It should start
 358with the standard "#!/bin/sh", and an
 359assignment to variable 'test_description', like this:
 360
 361        #!/bin/sh
 362
 363        test_description='xxx test (option --frotz)
 364
 365        This test registers the following structure in the cache
 366        and tries to run git-ls-files with option --frotz.'
 367
 368
 369Source 'test-lib.sh'
 370--------------------
 371
 372After assigning test_description, the test script should source
 373test-lib.sh like this:
 374
 375        . ./test-lib.sh
 376
 377This test harness library does the following things:
 378
 379 - If the script is invoked with command line argument --help
 380   (or -h), it shows the test_description and exits.
 381
 382 - Creates an empty test directory with an empty .git/objects database
 383   and chdir(2) into it.  This directory is 't/trash
 384   directory.$test_name_without_dotsh', with t/ subject to change by
 385   the --root option documented above.
 386
 387 - Defines standard test helper functions for your scripts to
 388   use.  These functions are designed to make all scripts behave
 389   consistently when command line arguments --verbose (or -v),
 390   --debug (or -d), and --immediate (or -i) is given.
 391
 392Do's, don'ts & things to keep in mind
 393-------------------------------------
 394
 395Here are a few examples of things you probably should and shouldn't do
 396when writing tests.
 397
 398Do:
 399
 400 - Put all code inside test_expect_success and other assertions.
 401
 402   Even code that isn't a test per se, but merely some setup code
 403   should be inside a test assertion.
 404
 405 - Chain your test assertions
 406
 407   Write test code like this:
 408
 409        git merge foo &&
 410        git push bar &&
 411        test ...
 412
 413   Instead of:
 414
 415        git merge hla
 416        git push gh
 417        test ...
 418
 419   That way all of the commands in your tests will succeed or fail. If
 420   you must ignore the return value of something, consider using a
 421   helper function (e.g. use sane_unset instead of unset, in order
 422   to avoid unportable return value for unsetting a variable that was
 423   already unset), or prepending the command with test_might_fail or
 424   test_must_fail.
 425
 426 - Check the test coverage for your tests. See the "Test coverage"
 427   below.
 428
 429   Don't blindly follow test coverage metrics; if a new function you added
 430   doesn't have any coverage, then you're probably doing something wrong,
 431   but having 100% coverage doesn't necessarily mean that you tested
 432   everything.
 433
 434   Tests that are likely to smoke out future regressions are better
 435   than tests that just inflate the coverage metrics.
 436
 437 - When a test checks for an absolute path that a git command generated,
 438   construct the expected value using $(pwd) rather than $PWD,
 439   $TEST_DIRECTORY, or $TRASH_DIRECTORY. It makes a difference on
 440   Windows, where the shell (MSYS bash) mangles absolute path names.
 441   For details, see the commit message of 4114156ae9.
 442
 443Don't:
 444
 445 - exit() within a <script> part.
 446
 447   The harness will catch this as a programming error of the test.
 448   Use test_done instead if you need to stop the tests early (see
 449   "Skipping tests" below).
 450
 451 - use '! git cmd' when you want to make sure the git command exits
 452   with failure in a controlled way by calling "die()".  Instead,
 453   use 'test_must_fail git cmd'.  This will signal a failure if git
 454   dies in an unexpected way (e.g. segfault).
 455
 456   On the other hand, don't use test_must_fail for running regular
 457   platform commands; just use '! cmd'.  We are not in the business
 458   of verifying that the world given to us sanely works.
 459
 460 - use perl without spelling it as "$PERL_PATH". This is to help our
 461   friends on Windows where the platform Perl often adds CR before
 462   the end of line, and they bundle Git with a version of Perl that
 463   does not do so, whose path is specified with $PERL_PATH. Note that we
 464   provide a "perl" function which uses $PERL_PATH under the hood, so
 465   you do not need to worry when simply running perl in the test scripts
 466   (but you do, for example, on a shebang line or in a sub script
 467   created via "write_script").
 468
 469 - use sh without spelling it as "$SHELL_PATH", when the script can
 470   be misinterpreted by broken platform shell (e.g. Solaris).
 471
 472 - chdir around in tests.  It is not sufficient to chdir to
 473   somewhere and then chdir back to the original location later in
 474   the test, as any intermediate step can fail and abort the test,
 475   causing the next test to start in an unexpected directory.  Do so
 476   inside a subshell if necessary.
 477
 478 - save and verify the standard error of compound commands, i.e. group
 479   commands, subshells, and shell functions (except test helper
 480   functions like 'test_must_fail') like this:
 481
 482     ( cd dir && git cmd ) 2>error &&
 483     test_cmp expect error
 484
 485   When running the test with '-x' tracing, then the trace of commands
 486   executed in the compound command will be included in standard error
 487   as well, quite possibly throwing off the subsequent checks examining
 488   the output.  Instead, save only the relevant git command's standard
 489   error:
 490
 491     ( cd dir && git cmd 2>../error ) &&
 492     test_cmp expect error
 493
 494 - Break the TAP output
 495
 496   The raw output from your test may be interpreted by a TAP harness. TAP
 497   harnesses will ignore everything they don't know about, but don't step
 498   on their toes in these areas:
 499
 500   - Don't print lines like "$x..$y" where $x and $y are integers.
 501
 502   - Don't print lines that begin with "ok" or "not ok".
 503
 504   TAP harnesses expect a line that begins with either "ok" and "not
 505   ok" to signal a test passed or failed (and our harness already
 506   produces such lines), so your script shouldn't emit such lines to
 507   their output.
 508
 509   You can glean some further possible issues from the TAP grammar
 510   (see https://metacpan.org/pod/TAP::Parser::Grammar#TAP-GRAMMAR)
 511   but the best indication is to just run the tests with prove(1),
 512   it'll complain if anything is amiss.
 513
 514Keep in mind:
 515
 516 - Inside the <script> part, the standard output and standard error
 517   streams are discarded, and the test harness only reports "ok" or
 518   "not ok" to the end user running the tests. Under --verbose, they
 519   are shown to help debugging the tests.
 520
 521
 522Skipping tests
 523--------------
 524
 525If you need to skip tests you should do so by using the three-arg form
 526of the test_* functions (see the "Test harness library" section
 527below), e.g.:
 528
 529    test_expect_success PERL 'I need Perl' '
 530        perl -e "hlagh() if unf_unf()"
 531    '
 532
 533The advantage of skipping tests like this is that platforms that don't
 534have the PERL and other optional dependencies get an indication of how
 535many tests they're missing.
 536
 537If the test code is too hairy for that (i.e. does a lot of setup work
 538outside test assertions) you can also skip all remaining tests by
 539setting skip_all and immediately call test_done:
 540
 541        if ! test_have_prereq PERL
 542        then
 543            skip_all='skipping perl interface tests, perl not available'
 544            test_done
 545        fi
 546
 547The string you give to skip_all will be used as an explanation for why
 548the test was skipped.
 549
 550End with test_done
 551------------------
 552
 553Your script will be a sequence of tests, using helper functions
 554from the test harness library.  At the end of the script, call
 555'test_done'.
 556
 557
 558Test harness library
 559--------------------
 560
 561There are a handful helper functions defined in the test harness
 562library for your script to use.
 563
 564 - test_expect_success [<prereq>] <message> <script>
 565
 566   Usually takes two strings as parameters, and evaluates the
 567   <script>.  If it yields success, test is considered
 568   successful.  <message> should state what it is testing.
 569
 570   Example:
 571
 572        test_expect_success \
 573            'git-write-tree should be able to write an empty tree.' \
 574            'tree=$(git-write-tree)'
 575
 576   If you supply three parameters the first will be taken to be a
 577   prerequisite; see the test_set_prereq and test_have_prereq
 578   documentation below:
 579
 580        test_expect_success TTY 'git --paginate rev-list uses a pager' \
 581            ' ... '
 582
 583   You can also supply a comma-separated list of prerequisites, in the
 584   rare case where your test depends on more than one:
 585
 586        test_expect_success PERL,PYTHON 'yo dawg' \
 587            ' test $(perl -E 'print eval "1 +" . qx[python -c "print 2"]') == "4" '
 588
 589 - test_expect_failure [<prereq>] <message> <script>
 590
 591   This is NOT the opposite of test_expect_success, but is used
 592   to mark a test that demonstrates a known breakage.  Unlike
 593   the usual test_expect_success tests, which say "ok" on
 594   success and "FAIL" on failure, this will say "FIXED" on
 595   success and "still broken" on failure.  Failures from these
 596   tests won't cause -i (immediate) to stop.
 597
 598   Like test_expect_success this function can optionally use a three
 599   argument invocation with a prerequisite as the first argument.
 600
 601 - test_debug <script>
 602
 603   This takes a single argument, <script>, and evaluates it only
 604   when the test script is started with --debug command line
 605   argument.  This is primarily meant for use during the
 606   development of a new test script.
 607
 608 - debug <git-command>
 609
 610   Run a git command inside a debugger. This is primarily meant for
 611   use when debugging a failing test script.
 612
 613 - test_done
 614
 615   Your test script must have test_done at the end.  Its purpose
 616   is to summarize successes and failures in the test script and
 617   exit with an appropriate error code.
 618
 619 - test_tick
 620
 621   Make commit and tag names consistent by setting the author and
 622   committer times to defined state.  Subsequent calls will
 623   advance the times by a fixed amount.
 624
 625 - test_commit <message> [<filename> [<contents>]]
 626
 627   Creates a commit with the given message, committing the given
 628   file with the given contents (default for both is to reuse the
 629   message string), and adds a tag (again reusing the message
 630   string as name).  Calls test_tick to make the SHA-1s
 631   reproducible.
 632
 633 - test_merge <message> <commit-or-tag>
 634
 635   Merges the given rev using the given message.  Like test_commit,
 636   creates a tag and calls test_tick before committing.
 637
 638 - test_set_prereq <prereq>
 639
 640   Set a test prerequisite to be used later with test_have_prereq. The
 641   test-lib will set some prerequisites for you, see the
 642   "Prerequisites" section below for a full list of these.
 643
 644   Others you can set yourself and use later with either
 645   test_have_prereq directly, or the three argument invocation of
 646   test_expect_success and test_expect_failure.
 647
 648 - test_have_prereq <prereq>
 649
 650   Check if we have a prerequisite previously set with test_set_prereq.
 651   The most common way to use this explicitly (as opposed to the
 652   implicit use when an argument is passed to test_expect_*) is to skip
 653   all the tests at the start of the test script if we don't have some
 654   essential prerequisite:
 655
 656        if ! test_have_prereq PERL
 657        then
 658            skip_all='skipping perl interface tests, perl not available'
 659            test_done
 660        fi
 661
 662 - test_external [<prereq>] <message> <external> <script>
 663
 664   Execute a <script> with an <external> interpreter (like perl). This
 665   was added for tests like t9700-perl-git.sh which do most of their
 666   work in an external test script.
 667
 668        test_external \
 669            'GitwebCache::*FileCache*' \
 670            perl "$TEST_DIRECTORY"/t9503/test_cache_interface.pl
 671
 672   If the test is outputting its own TAP you should set the
 673   test_external_has_tap variable somewhere before calling the first
 674   test_external* function. See t9700-perl-git.sh for an example.
 675
 676        # The external test will outputs its own plan
 677        test_external_has_tap=1
 678
 679 - test_external_without_stderr [<prereq>] <message> <external> <script>
 680
 681   Like test_external but fail if there's any output on stderr,
 682   instead of checking the exit code.
 683
 684        test_external_without_stderr \
 685            'Perl API' \
 686            perl "$TEST_DIRECTORY"/t9700/test.pl
 687
 688 - test_expect_code <exit-code> <command>
 689
 690   Run a command and ensure that it exits with the given exit code.
 691   For example:
 692
 693        test_expect_success 'Merge with d/f conflicts' '
 694                test_expect_code 1 git merge "merge msg" B master
 695        '
 696
 697 - test_must_fail [<options>] <git-command>
 698
 699   Run a git command and ensure it fails in a controlled way.  Use
 700   this instead of "! <git-command>".  When git-command dies due to a
 701   segfault, test_must_fail diagnoses it as an error; "! <git-command>"
 702   treats it as just another expected failure, which would let such a
 703   bug go unnoticed.
 704
 705   Accepts the following options:
 706
 707     ok=<signal-name>[,<...>]:
 708       Don't treat an exit caused by the given signal as error.
 709       Multiple signals can be specified as a comma separated list.
 710       Currently recognized signal names are: sigpipe, success.
 711       (Don't use 'success', use 'test_might_fail' instead.)
 712
 713 - test_might_fail [<options>] <git-command>
 714
 715   Similar to test_must_fail, but tolerate success, too.  Use this
 716   instead of "<git-command> || :" to catch failures due to segv.
 717
 718   Accepts the same options as test_must_fail.
 719
 720 - test_cmp <expected> <actual>
 721
 722   Check whether the content of the <actual> file matches the
 723   <expected> file.  This behaves like "cmp" but produces more
 724   helpful output when the test is run with "-v" option.
 725
 726 - test_cmp_rev <expected> <actual>
 727
 728   Check whether the <expected> rev points to the same commit as the
 729   <actual> rev.
 730
 731 - test_line_count (= | -lt | -ge | ...) <length> <file>
 732
 733   Check whether a file has the length it is expected to.
 734
 735 - test_path_is_file <path> [<diagnosis>]
 736   test_path_is_dir <path> [<diagnosis>]
 737   test_path_is_missing <path> [<diagnosis>]
 738
 739   Check if the named path is a file, if the named path is a
 740   directory, or if the named path does not exist, respectively,
 741   and fail otherwise, showing the <diagnosis> text.
 742
 743 - test_when_finished <script>
 744
 745   Prepend <script> to a list of commands to run to clean up
 746   at the end of the current test.  If some clean-up command
 747   fails, the test will not pass.
 748
 749   Example:
 750
 751        test_expect_success 'branch pointing to non-commit' '
 752                git rev-parse HEAD^{tree} >.git/refs/heads/invalid &&
 753                test_when_finished "git update-ref -d refs/heads/invalid" &&
 754                ...
 755        '
 756
 757 - test_write_lines <lines>
 758
 759   Write <lines> on standard output, one line per argument.
 760   Useful to prepare multi-line files in a compact form.
 761
 762   Example:
 763
 764        test_write_lines a b c d e f g >foo
 765
 766   Is a more compact equivalent of:
 767        cat >foo <<-EOF
 768        a
 769        b
 770        c
 771        d
 772        e
 773        f
 774        g
 775        EOF
 776
 777
 778 - test_pause
 779
 780        This command is useful for writing and debugging tests and must be
 781        removed before submitting. It halts the execution of the test and
 782        spawns a shell in the trash directory. Exit the shell to continue
 783        the test. Example:
 784
 785        test_expect_success 'test' '
 786                git do-something >actual &&
 787                test_pause &&
 788                test_cmp expected actual
 789        '
 790
 791 - test_ln_s_add <path1> <path2>
 792
 793   This function helps systems whose filesystem does not support symbolic
 794   links. Use it to add a symbolic link entry to the index when it is not
 795   important that the file system entry is a symbolic link, i.e., instead
 796   of the sequence
 797
 798        ln -s foo bar &&
 799        git add bar
 800
 801   Sometimes it is possible to split a test in a part that does not need
 802   the symbolic link in the file system and a part that does; then only
 803   the latter part need be protected by a SYMLINKS prerequisite (see below).
 804
 805Prerequisites
 806-------------
 807
 808These are the prerequisites that the test library predefines with
 809test_have_prereq.
 810
 811See the prereq argument to the test_* functions in the "Test harness
 812library" section above and the "test_have_prereq" function for how to
 813use these, and "test_set_prereq" for how to define your own.
 814
 815 - PYTHON
 816
 817   Git wasn't compiled with NO_PYTHON=YesPlease. Wrap any tests that
 818   need Python with this.
 819
 820 - PERL
 821
 822   Git wasn't compiled with NO_PERL=YesPlease.
 823
 824   Even without the PERL prerequisite, tests can assume there is a
 825   usable perl interpreter at $PERL_PATH, though it need not be
 826   particularly modern.
 827
 828 - POSIXPERM
 829
 830   The filesystem supports POSIX style permission bits.
 831
 832 - BSLASHPSPEC
 833
 834   Backslashes in pathspec are not directory separators. This is not
 835   set on Windows. See 6fd1106a for details.
 836
 837 - EXECKEEPSPID
 838
 839   The process retains the same pid across exec(2). See fb9a2bea for
 840   details.
 841
 842 - PIPE
 843
 844   The filesystem we're on supports creation of FIFOs (named pipes)
 845   via mkfifo(1).
 846
 847 - SYMLINKS
 848
 849   The filesystem we're on supports symbolic links. E.g. a FAT
 850   filesystem doesn't support these. See 704a3143 for details.
 851
 852 - SANITY
 853
 854   Test is not run by root user, and an attempt to write to an
 855   unwritable file is expected to fail correctly.
 856
 857 - PCRE
 858
 859   Git was compiled with support for PCRE. Wrap any tests
 860   that use git-grep --perl-regexp or git-grep -P in these.
 861
 862 - LIBPCRE1
 863
 864   Git was compiled with PCRE v1 support via
 865   USE_LIBPCRE1=YesPlease. Wrap any PCRE using tests that for some
 866   reason need v1 of the PCRE library instead of v2 in these.
 867
 868 - LIBPCRE2
 869
 870   Git was compiled with PCRE v2 support via
 871   USE_LIBPCRE2=YesPlease. Wrap any PCRE using tests that for some
 872   reason need v2 of the PCRE library instead of v1 in these.
 873
 874 - CASE_INSENSITIVE_FS
 875
 876   Test is run on a case insensitive file system.
 877
 878 - UTF8_NFD_TO_NFC
 879
 880   Test is run on a filesystem which converts decomposed utf-8 (nfd)
 881   to precomposed utf-8 (nfc).
 882
 883 - PTHREADS
 884
 885   Git wasn't compiled with NO_PTHREADS=YesPlease.
 886
 887Tips for Writing Tests
 888----------------------
 889
 890As with any programming projects, existing programs are the best
 891source of the information.  However, do _not_ emulate
 892t0000-basic.sh when writing your tests.  The test is special in
 893that it tries to validate the very core of GIT.  For example, it
 894knows that there will be 256 subdirectories under .git/objects/,
 895and it knows that the object ID of an empty tree is a certain
 89640-byte string.  This is deliberately done so in t0000-basic.sh
 897because the things the very basic core test tries to achieve is
 898to serve as a basis for people who are changing the GIT internal
 899drastically.  For these people, after making certain changes,
 900not seeing failures from the basic test _is_ a failure.  And
 901such drastic changes to the core GIT that even changes these
 902otherwise supposedly stable object IDs should be accompanied by
 903an update to t0000-basic.sh.
 904
 905However, other tests that simply rely on basic parts of the core
 906GIT working properly should not have that level of intimate
 907knowledge of the core GIT internals.  If all the test scripts
 908hardcoded the object IDs like t0000-basic.sh does, that defeats
 909the purpose of t0000-basic.sh, which is to isolate that level of
 910validation in one place.  Your test also ends up needing
 911updating when such a change to the internal happens, so do _not_
 912do it and leave the low level of validation to t0000-basic.sh.
 913
 914Test coverage
 915-------------
 916
 917You can use the coverage tests to find code paths that are not being
 918used or properly exercised yet.
 919
 920To do that, run the coverage target at the top-level (not in the t/
 921directory):
 922
 923    make coverage
 924
 925That'll compile Git with GCC's coverage arguments, and generate a test
 926report with gcov after the tests finish. Running the coverage tests
 927can take a while, since running the tests in parallel is incompatible
 928with GCC's coverage mode.
 929
 930After the tests have run you can generate a list of untested
 931functions:
 932
 933    make coverage-untested-functions
 934
 935You can also generate a detailed per-file HTML report using the
 936Devel::Cover module. To install it do:
 937
 938   # On Debian or Ubuntu:
 939   sudo aptitude install libdevel-cover-perl
 940
 941   # From the CPAN with cpanminus
 942   curl -L http://cpanmin.us | perl - --sudo --self-upgrade
 943   cpanm --sudo Devel::Cover
 944
 945Then, at the top-level:
 946
 947    make cover_db_html
 948
 949That'll generate a detailed cover report in the "cover_db_html"
 950directory, which you can then copy to a webserver, or inspect locally
 951in a browser.